Note: these mistakes cannot be caught by spell-check

She felt accepted by everyone in the family, except her mother-in-law.

Of course the strychnine affected him.  The effects of that poison are deadly.

In other words, affect is a verb and effect is a noun.  Note, however, that both words have secondary meanings that reverse this rule.  Affect as a noun is also a psychological term meaning feeling or emotion, or the feeling and emotion associated with an object; effect as a verb is a highly formal (verging on arch) way of saying “make.” These usages should be far less common than those above.

Because Janis heard her mother sing that song every day during her childhood, it carried an unusual degree of affect for her.

By lowering the interest rates in December, the Federal Reserve was attempting to effect a change in people’s buying habits.

She wondered aloud if she would be allowed to compete in the spelling bee.

The criminal to whom I alluded yesterday eluded capture for another two weeks before an informant turned him in.

In a recent interview, Penn and Teller made an allusion to a famous illusion Harry Houdini had performed in the 1920s.

“Keep these screws apart from the others,” said Jim, as he fitted the Ikea bookcase together.  “We’ll need them before we’re done, and nothing is more frustrating when you build these things than having to hunt around looking for a part.”

In other words, a part is an article plus noun and means “a piece of a whole”; apart is an adjective meaning “away from” or “separate.”  A part is often followed by of; apart is often followed by from. 

Our dogs are both getting very old.

The study shows no correlation, let alone a causal relationship, between casual clothing and disciplinary problems.

In announcing the site for the construction of the new city hospital, the mayor cited the environmental impact study he had commissioned the year before.  You can find the study on the city website, but if you quote it in your paper, be sure to cite it properly.

Her clothes were made out of the finest silk and linen.  She had sewn them herself from some old tablecloths she found in her attic.  The cloth from which they were made came from China.

“Henry,” said the head chef, “this balsamic reduction complements the fruit in this dessert remarkably well.”
Henry stammered his thanks but was too nervous to say more.  He was not used to compliments from his boss, and he half-expected Monsieur Robert to follow up with a sarcastic aside.

In other words, complement means “to complete,” or, more casually, “to accompany in a favorable way,” whereas compliment means “to say nice things about.”

Consciously or not, Terry was taking advantage of Pandora when he asked her to stay home with him that night instead of going to the concert.  She had a guilty conscience, though it was hardly her fault that he had broken his leg and been knocked unconscious, even if she had invited him on the ski trip.  He was the one who insisted on skiing a double-black-diamond trail.  She has always been too conscientious for her own good.

In other words, the conscience (a noun) is the part of our minds that makes us feel guilty or responsible, that keeps us from acting badly or unfairly; conscientious is the adjective form, used to describe someone with a highly developed conscience.  Conscious (an adjective) means being aware or awake; consciousness is the noun form.

Defuse/Diffuse

You had better defuse that bomb quickly, or it will diffuse our bodies over a wide area.

She was definitely angry; she shook her fist at him and said defiantly, “I have lived here my entire life, and I will not sell you this land for any amount of money!”

Note:  This is actually a spelling error because these words should not be pronounced remotely alike: DEF-in-it-lee vs. de-FI [long i, as in TIE]-ent-lee.

Even in Dorothea’s old age, the smell of hibiscus would elicit memories of Tahiti, Philippe, and their passionate and illicit affair in the summer of her twenty-first year.

I could have, I should have, and I would have, but I didn’t and I’m sorry. [Not “I could of, I should of, I would of,” etc.]

Note:  Authors writing in dialect — e.g. Mark Twain, Flannery O’Connor, John Kennedy Toole — often break this rule.

A vast horde of adventurers, thieves, and mountebanks invaded the city in search of the hoard of treasure they had heard was hidden there.

Note: the first is a contraction of “it is”; the second is a possessive meaning “belonging to it.”  Also, its is the only possessive that does not contain an apostrophe.

She felt as if she needed to lie down. She just wanted to lay her head on the pillow and go to sleep.  But she lay in bed for hours, and nothing happened.  It was not until her sister finally called her that afternoon that she laid her worries aside.

Lay is a transitive verb, which means it takes a direct object.  A gambler can lay his cards on the table, and a boxer can lay an opponent out with one punch, but one does not lay down. Lie is an intransitive verb, which means it cannot take a direct object.  You can lie down, or lie in bed, but you cannot lie something.  What gets confusing is that the past tense of lie is also lay, whereas the past tense of lay is laid.

I led my daughter to the counter, where she bought ink for her pen and lead for her mechanical pencil.  I wonder where her interest in writing will lead her?

Note:  The usual problem here is writing “lead” when you mean “led.”

Let’s go to the theatre on 4th Street. My uncle is the manager there and he lets me in for free.

Note: the first is a contraction of the verb “let” and “us”; the second is just the third-person singular form of the verb (meaning “allow”).

Bobby was loath to take Algebra II his sophomore year in high school; he liked mathematics well enough, but the teacher, Mr. Giddens, coached wrestling, and Bobby loathed him.

The first is an adjective meaning “reluctant”; the second is a verb meaning “despise.”

That key-chain is so loose that I am afraid you might lose your keys.

Note:  The former is usually an adjective; the latter is a verb, but the same rule applies to the other forms of the words:

I saw Mr. Burns loosing his dogs on Bart. Losing his money didn’t make him any less mean.

As Ben picked out a pair of even baggier jeans, his father said, “Wearing your pants any looser than the ones you have now will make you look like a loser.”

There may be a good reason they never showed up.  Maybe they missed their flight.

The first is a verb phrase; the second is an adverb.

“Mother, I just want to look at the mountains. Those peaks are spectacular,” said Hermione as she peeked through the window blinds. But it was really Lars, the ski instructor, who had piqued her interest.

Prejudice always infuriated Dr. Prendergrast, no matter where or in whom he encountered it, perhaps because he grew up in a deeply prejudiced family.

Do you suppose he will accept the paper late?  It was supposed to be handed in Monday.

She used to like TV on the Radio more than Arcade Fire; then she changed her mind.

They’re going over there to visit their relatives.

The pronunciation of the third word should be different from that of the first two, something like “THAY-R” instead of “THAIR” — that is, the vowel sound is longer in “they’re.”

One should not be surprised when a despot who has seized the throne is himself overthrown.

I went to Prague with two friends.  We stopped in Budapest and Vienna, too.

I used to play that piano every day; now I just use it as a table.

Whether the weather is good or not, the wedding will be Saturday.

We’re going to visit Westminster Abbey, where you were yesterday.

The pronunciation of these words should be different, something like “WUR,” “WEER,” and either “WAIR” or, more traditionally, “HWAIR” (the “wh" combination, as Stewie Griffin knows, was long pronounced like “hw” and still is in some places).

You’re going to ruin your ears if you keep blasting your car stereo at full volume.

A lot of people like jazz.  My friend Thelonius likes it a lot.

Note: many and much are usually preferable: Many people like jazz. My friend Thelonius likes it very much.

Note:  Spellcheck will not catch “allot” because it is a different word (meaning to allocate or parcel out)

Is that all right with you?

Note: alright appeared a mere seventy years after all right, so some style guides argue that it should be acceptable.  More, however, still do not, and even the ones that do usually list all right as preferable.  (Of course, in dialect the rules are different; you might even see a’ight in dialect.)

Have you already set the table?

Note: this only applies to already used as an adverb; in a phrase in which all refers to a group and ready functions as an adjective, the words should not be combined: “Are your friends all done with finals?  Mine are all ready for vacation.”

Other words that frequently give people problems

The difference between these words is the degree of interruption.  Continuous usually refers to physical description and implies no interruption, as in “His eyebrows grew so close together that they formed one continuous line across his face.”  Continual usually refers to time and implies something repetitive to the point it becomes virtually constant, as in “Little Ethan’s continual banging of his toy drum had given Sarah a headache.”  Repeated means something that happens again and again, but with intervals, as in “Steve became a successful attorney, despite his repeated failure to pass the bar exam.”

Note that these rules also apply to the adverbial form (continuously/continually/repeatedly).

These words cannot serve as all-purpose replacements for describe, because both apply the visual nature of description to complex phenomena.  You can depict the chaos of war, but you cannot depict a tree or a house.  Similarly, an author can portray the struggle of the poor to rise in society — and, in a slightly different use of the word, an actor can portray Thomas Jefferson as a young man — but no one portrays Thanksgiving dinner (unless they portray it in a symbolic way, such as a baseball game portrayed as a pagan pastoral ritual).

Literally, these words mean “to call out of” and “to call upon.”  Evoke is usually used to describe how a stimulus of some kind causes an emotional or personal reaction: “This photograph of Sarah playing with her twin brother when they were seven always evokes happy memories of the house on Stanton Street,” and “Reading Lord Byron’s ‘Darkness’ evokes vivid images of destruction and feelings of horror in me.”  Invoke, on the other hand, describes some sort of call for help, usually an appeal to a higher authority:  “Elihu Root surprised the justices by invoking the First Amendment in his summation,” and “As he spoke the twisted words from the ancient text, all present realized what he intended:  to invoke the aid of Cthulu and all his dark minions.  And then they knew his lust for power had finally driven him mad.”

Human has more traditionally been an adjective than a noun. Thus, the phrase is “human being,” i.e. a being who is human.  However, an equally acceptable (and shorter and simpler) term for an individual human being is person, and people is a perfectly fine word for a group of individuals.  Human does make sense in the scientific sense, when one is considering homo sapiens sapiens as a species, as for example in an anthropology essay. But while one can find an occasional past use of human as a substitute for person, the growing use of humans for people in general seems to have developed out of science fiction.  Having a nasty alien race call human beings people makes them seem less nasty, especially when you can have them spondaically (i.e. with equally stressed syllables in the word) grunt “KILL ALL the HYOO-MAHNZ.”  But sci-fi nerds should not have such power over the language, so unless you can prove Klingon ancestry or have some particular reason for emphasizing our species (rarely the case), it is usually better to choose between person/people and human being(s).

The politician arose from his desk, and gravely addressed the reporters, “I don’t know what you are implying, gentlemen, but I infer from your tone that you think I have been dishonest, and I must tell you, sirs, I do not like that implication.  Who knows what inference the voters may take from it?”

In other words, the speaker or writer implies, and the listener or reader infers.

Properly a noun, as in “What impact do you think the plant closing will have on the economy here?”  Although nouns can occasionally be used as verbs to create more vivid language, impact should not be considered a general replacement for affect.  Using it this way often sounds ridiculous, as in “The high temperatures will impact the runners strongly today.”  Impact is vastly overused these days.

This word is often hyperbole.  Few things are actually opposite, and the chances go down the more complex they are.  Above all, people (including literary characters) are never opposite. You cannot say, “Laertes is the opposite of Hamlet,” for example, because while they have certain traits that are different, they also have much in common, and this will virtually always be true of any characters.  Also, never modify this word with adjectives such as complete or total or very.  It is an absolute, and should never be intensified, although you can modify it with words such as nearly or almost.

This is the proper adjective to describe something that prevents something from happening; there is no need for the recent coinage (common in ads for new medicines and car maintenance) preventative.

Quote is properly a verb, as in “He always quotes Oscar Wilde when he wants to sound witty.”  Quote is slang as a noun; the correct noun form is quotation.  Unless you are hanging around a newsroom or starring in a production of The Front Page, don’t say something like, “This is a revealing quote.” 

This is the proper word when you want to create a transition that means in any event or whatever the case; there is no such word as irregardless.

An extraordinarily weak word, especially when used in the passive voice as in “This is related to [etc.].”   The problem is there are many kinds of relationships: if A and B are alike, they have a relationship; if A and B are opposite, they also have a relationship; if A causes B they have a relationship, but a different relationship than if B causes A, or if both are caused by C.  Relate fails to make the relationship clear.  Find the appropriate verb to describe the relationship instead.

Similarly, do not just say that the reader or the audience can relate to a character; do you mean sympathize with?  Empathize with?  Identify with?  Admire?  In this case, find the appropriate verb to describe the emotion.  Avoid the word “relatable,” which literally makes no sense in most circumstances: usually, one is not relating the thing being described to something else but relating oneself to the thing being described, so the ability (as in “-able”) to relate is one’s own, not the thing’s.  (Confused?  Just avoid the word!)

Simplistic is not a fancy way of saying simple.  Simplistic is a pejorative, i.e. an insult, whereas simple is neutral and can even be complimentary. If you say something is simplistic, you mean that it is shallow, unsophisticated, misleading, and even stupid.  If you say something is simple, you mean it is not complicated, and that can be a good thing.  For example, if your history professor writes “Your analysis of the Protestant Reformation is simplistic” on your paper, you can expect a poor grade.  But a music review that says “All of the songs on the CD are based on simple medieval melodies” may well be a four-star review.

This word means “all the way through” and frequently causes two problems.  First, people use it when it does not apply, for example when something only happens for part of the time, or stops happening after a certain point.  You cannot say, for instance, that Edward Thomas wrote poetry throughout World War I when he was killed long before the war ended.  The other problem is that people routinely use a phrase such as “throughout the entire” even though it is redundant:  throughout already implies entire, unless modified by some other phrase. For example, you could write “The two teams stayed close throughout the first half, but in the third quarter the Patriots pulled away,” but if you write “The two teams stayed close throughout,” then you are implying that the score stayed close for the entire game.

This word is not a fancy way of saying “different.”  It is an absolute (like opposite) and literally means that whatever is being described is the only one of its kind. Therefore, you cannot sensibly modify this adjective with adverbs such as very, extremely, fairly, rather, quite, etc. 

These are almost mutually exclusive means of measurement.  The rule is that you should use number when something can be counted, and amount when it can only be measured in some other way.  Thus, someone can drink an amount of (or a little, less, much, etc.) beer, but the same person drinks a number of (or few, fewer, many, several etc.) beers.  Another way to think of it is that you use number when the noun can become plural; and amount when it cannot, as in “Bobby is sick; he ate too many hot dogs and too much chicken.”  (However, you would say “How many chickens do you seen in the yard?” because live chickens can be counted.)  Only more works for both amount and number.  Other examples:

“I have a huge amount of homework to do this weekend.”
“Yeah?  Well I have fewer classes than you do, but I still have several papers to write.”
“True, but I have less time after work”
“What do you mean?  We work the same number of hours.”     
“Yes, but my shift is later, so you have more time after work to write, more hours before you are tired.”

And yes, the signs at most grocery stores — “X items or less” — are wrong; they should say “X items or fewer.” (Locally, Wegman’s is the only store that uses the correct phrase:  score one for grammar!)

Common Punctuation Problems

If a comma is needed with a conjunction, it goes before the conjunction.

Wrong:  The blood-dimmed tide is loosed and, everywhere the ceremony of innocence is drowned.
Right:  The blood-dimmed tide is loosed, and everywhere the ceremony of innocence is drowned.

This problem occurs because people confuse adverbs and conjunctions, most commonly (but not always) at the beginning of a sentence. When starting a sentence with an adverb such as However, a comma is required.  But a comma is incorrect after coordinating conjunctions (the problem happens especially with but and yet) and subordinating conjunction (especially although):

Wrong:  But, she never returned to her hometown.
Right:  But she never returned to her hometown.

Wrong:  Although, Machiavelli has a reputation for being ruthless and amoral, in reality he was a conscientious public servant.
Right:  Although Machiavelli has a reputation for being ruthless and amoral, in reality he was a conscientious public servant.

The only time you should put a comma after a conjunction is when another phrase follows and interrupts the main phrase:

Right: Yet, she reflected, the opportunity might not come again.

Although not an error per se, omitting the comma before the conjunction and last item in a series can be confusing.  Use a comma and conjunction after the next-to-last element instead of merely a conjunction in any series of three or more items, especially if the series contains phrases (not just single words). 

Confusing:  The actors in the play included a trained Shakespearian from London who had never played a role more important than “Second Lord,” an alcoholic grandmother who hadn’t been on stage in a dozen years, a former Academy Award nominee who now couldn’t remember more than two lines in a row without a cue card, an aging soap opera heartthrob with an insatiable hunger for cocaine and various ingenue refugees from B-level horror flicks — all of whom couldn’t stand one another. 

Does the aging soap opera heartthrob hunger for cocaine and ingenues?  Or are the ingenues performing in the play?  We have no way of knowing here.

Not confusing:  The actors in the play included a trained Shakespearian from London who had never played a role more important than “Second Lord,” an alcoholic grandmother who hadn’t been on stage in a dozen years, a former Academy Award nominee who now couldn’t remember more than two lines in a row without a cue card, an aging soap opera heartthrob with an insatiable hunger for cocaine, and various ingenue refugees from B-level horror flicks — all of whom couldn’t stand one another. 

In this case, the ingenues are clearly in the play.

Dashes and hyphens are not the same thing.

A hyphen, which looks like this - connects what is on either side of it; a dash, which looks like this — separates what comes before it from what comes after it.  Use a hyphen for a hyphenated word, or (rarely necessary nowadays) to connect the first part of a word on one line to the last part on another.  Use a dash to interrupt a sentence, similar to a colon or a parenthesis, except that a dash gives more emphasis, whereas parentheses suggest that what is inside them can be ignored.  You can find a dash on the insert menu in most word processing programs; otherwise you may substitute two hyphens -- like that (some word processing programs will automatically change this to a dash anyway).  In any case, to make both easier to recognize, it helps to put spaces around dashes but not around single hyphens.

Wrong:  World War I ace Manfred von Richthofen, known as The Red Baron, and his brother Lothar were members of a well—known aristocratic Prussian family-surprisingly their cousin Frieda was married to the famous British writer D. H. Lawrence.
Right:  World War I ace Manfred von Richthofen, known as The Red Baron, and his brother Lothar were members of a well-known aristocratic Prussian family — surprisingly, their cousin Frieda was married to the famous British writer D. H. Lawrence.
Also permissible:  World War I ace Manfred von Richthofen, known as The Red Baron, and his brother Lothar were members of a well-known aristocratic Prussian family -- surprisingly, their cousin Frieda was married to the famous British writer D. H. Lawrence.

You should generally avoid exclamation points (except in dialogue or when stating a command).  Let your words speak for themselves.  Yelling does not make you more persuasive.

Wrong:  In effect, Tom Buchanan is a vicious and unrepentant murderer!
Right:  In effect, Tom Buchanan is a vicious and unrepentant murderer.

Common Stylistic Errors (some are incredibly annoying, some just best avoided)

Wrong:  Now, you would think he’d have been embarrassed.  Well, he wasn’t.  See, he didn’t care.
Right:  You would think he’d have been embarrassed.  He wasn’t.   He didn’t care.

Note: These words are different from transition words such as however, nonetheless, moreover, etc.  Those words help the reader understand the relationship between the information presented in the prior sentence and the information that follows; conversational words merely take up space without providing any real information.

Wrong:  I didn’t say nothing after that.
Right:  I didn’t say anything after that.
Or:  I said nothing after that.

Wrong:  Hamlet believes Rosencrantz and Guildenstern have betrayed him. So he has them killed.
Right:  Hamlet believes Rosencrantz and Guildenstern have betrayed him, so he has them killed.
Also right:  Hamlet believes Rosencrantz and Guildenstern have betrayed him. Therefore, he has them killed.
Better:  Hamlet has Rosencrantz and Guildenstern killed because he believes they have betrayed him.
Also better:  Believing Rosencrantz and Guildenstern have betrayed him, Hamlet has them killed.

One exception to this rule is when so introduces a dependent clause, as in “So that there was no danger of Sir Cecil showing up for his speech drunk, I assigned my assistant Penelope to watch over him all day.”  In that case, the normal syntax of the sentence (“I assigned my assistant Penelope to watch over him all day so that there was no danger of Sir Cecil showing up for his speech drunk”) has simply been inverted, which is perfectly acceptable.  But unless you are sure of what you are doing, it is best to avoid the problem.

Wrong:  He is so ugly.
Right:  He is so ugly that blind people who commit crimes should have to feel his face as a punishment.
Wrong:  She was such a fan of James Dean.
Right:  She was such a fan of James Dean she bought all three of his films on Blu-Ray even though she already owned them all DVD.

Wrong:  The fact is Joe Gibbs was the best football coach of the 1980’s.
Right:  Because he won three championships with three different quarterbacks — none of whom has even a remote chance of being inducted into the Hall of Fame — Joe Gibbs was the best football coach of the 1980s.

Wrong:  The pianist that played was over eighty years old.
Right:  The pianist who played was over eighty years old.

Wrong:  She recited the poem, that she had memorized fifty years earlier, flawlessly.  Seeing all those people cheering when she was done was something which I will never forget.
Right:  She recited the poem, which she had memorized fifty years earlier, flawlessly.  Seeing all those people cheering when she was done was something that I will never forget.

Note that sometimes context makes the difference. Both of the following phrases could be correct:

The house that burned down was over two-hundred years old.

The house, which burned down, was over two-hundred years old.

The difference is that the first sentence would be appropriate if it were in the context of a story or conversation about a fire; in that case, the house burning down is crucial information.  The second sentence would be appropriate if the house burning down is merely incidental information, for example if the story or conversation is about the early history of a particular house.

Wrong:  For exercise, I like to swim, to do yoga, and playing basketball.
Right:  For exercise, I like swimming, doing yoga, and playing basketball.

If you cannot gracefully make one of the series into the same form as the rest, you can get around the problem by putting the last item in the series in a separate phrase:

Wrong:  Richard Francis Burton became famous for his explorations, his many books, and shocking the Victorian public with his admiration for supposedly more primitive cultures.
Right:   Richard Francis Burton became famous for his explorations and his many books, and infamous for shocking the Victorian public with his admiration for supposedly more primitive cultures.