The meanings of words in the English language often change over time. Sometimes a meaning becomes entirely reversed; for example, nice used to be a negative word meaning "stupid", "wanton", or "lazy", but now means "agreeable", "pleasant" or "attractive". This process is part of the natural evolution of a language, and although it may meet with resistance from prescriptive grammarians, changes that stick are eventually noted in dictionaries.

The list that follows is meant to include only words whose misuse is deprecated by most usage writers, editors, and other arbiters of so-called "correct" English. It is possible that some of the meanings marked Non-standard will pass into Standard English in the future, but at this time all of the below Non-standard phrases are likely to be marked as incorrect by English teachers or changed by editors if used in a work submitted for publication. Several of the examples are homonyms or pairs of similarly spelled words which are often confused.

In any case, the words listed below are consistently used in ways that major English dictionaries do not condone in any definition. See list of English words with disputed usage for words that are used in ways that are deprecated by some usage writers but are condoned by some dictionaries.

There may be regional variations in grammar, spelling and word-use, especially between different English-speaking countries. Such differences are not seen as incorrect once they have gained widespread acceptance in a particular country.


List
Accept and except. While they both sound similar, except is a preposition that means "apart from", while accept is a verb that means "agree with", "take in" or "receive". Except is also rarely used as a verb, meaning to leave out.
Standard: We accept all major credit cards, except Diners Club.
Standard: Men are fools... present company excepted! (Which means "present company excluded")
Non-standard: I had trouble making friends with them; I never felt excepted.
Non-standard: We all went swimming, accept for Jack.

Acute and chronic. Acute means "sharp", as an acute illness is one that rapidly worsens and reaches a crisis. A chronic illness may also be a severe one, but it is long-lasting or lingering.
Standard: She was treated with epinephrine during an acute asthma attack.
Standard: It is not a terminal illness, but it does cause chronic pain.
Non-standard: I have suffered from acute asthma for twenty years.
Non-standard: I just started feeling this chronic pain in my back.

Affect and effect. The verb affect means "to influence something," and the noun effect means "the result of." Effect can also be a somewhat formal verb that means "to cause [something] to be," while affect as a noun has a technical meaning in psychology: an emotion or subjectively experienced feeling.
Standard. This poem affected me so much that I cried.
Standard. Temperature has an effect on reaction spontaneity.
Standard. The dynamite effected the wall's collapse.
Standard. He seemed completely devoid of affect.
Non-standard. The rain effected our plans for the day.
Non-standard. We tried appeasing the rain gods, but without affect.

Aggravate and mitigate. "Aggravate" means to make worse. "Mitigate" means to make less bad. "Mitigating factor" refers to something that affects someone's case by lessening the degree of blame, not anything that has any effect at all.

Assume: to suppose to be true, especially without proof, and presume: to take for granted as being true in the absence of proof to the contrary. "Presume" can also mean "take excessive liberties", as in the adjective form "presumptious".

Brought and bought. Brought is the past tense and past participle of the verb to bring, and bought is the past tense and past participle of the verb to buy. Confusion of the two occurs particularly in speech.

Cache and cachet. A cache (pronounced kash) is a storage place from which items may be quickly retrieved. A cachet (pronounced kash-AY) is a seal or mark, like a wax seal on an envelope or a mark of authenticity on a product. Note that cachet is almost always used figuratively to mean "marked by excellence, distiction or superiority".
Standard: The pirates buried a cache of jewels near the coast.
Standard: Living in New York City definitely has a certain cachet.
Non-standard: If your web browser is running slowly, try emptying the cachet.

Cant and can't. There are several meanings for the word cant (without an apostrophe); however, none of them is "unable to". One meaning of cant is "a kind of slang or jargon spoken by a particular group of people". Can't is a contraction of cannot.
Standard: I can't understand the dialogue in this book because it's written in cant.
Non-standard: I cant swim; I've never taken lessons.

Comprise To comprise means "to consist of" or "to include". One sometimes meets the redundant usages "to comprise of" or "to be comprised of". (These may arise by confusion with the correct forms "to consist of" and "to be composed of").
Standard: The English Wikipedia comprises more than 1 million articles.
Non-standard: The English Wikipedia comprises of more than 1 million articles.
Non-standard: The English Wikipedia is comprised of more than 1 million articles.
Standard, alternative: The English Wikipedia is composed of more than 1 million articles.
Standard, alternative: The English Wikipedia includes more than 1 million articles.
Standard, alternative: The English Wikipedia consists of more than 1 million articles.

Discreet and discrete. "Discrete" means "having separate parts", as opposed to continuous. "Discreet" means "circumspect".

Diffuse and Defuse. Diffusion refers to the dispersal of fluidic or solid wastes or otherwise into a medium, whereas defusion refers to the disengagement of an electromagnetic field, generally by dissolving the harmony of the magnetic field and allowing the surrounding medium to reclaim the energy released from the field.

Economic and economical. "Economic" means "having to do with the economy". "Economical" means "financially prudent".
Standard: Buying in bulk can often be the most economical choice.
Non-standard: Leading economical indicators suggest that a recession may be on the horizon.

Eminent and imminent.

Exacerbate and exasperate. "Exacerbate" means to make worse. "Exasperate" means to exhaust, usually someone's patience.

Flesh and Flush. To flesh out is to put flesh to a skeleton, or to add substance to an incomplete rendering. To flush out is to cause game fowl to take to flight, or to frighten any quarry from a place of concealment.
Standard: The forensic pathologist will flesh out the skull with clay.
Standard: The beaters flushed out the game with drums and torches.
Non-standard: This outline is incomplete and must be flushed out.

Flounder and Founder. To flounder is to be clumsy, confused, indecisive or to flop around like a fish out of water. A flounder is also a type of flatfish. To founder is to fill with water and sink.
Standard: The ship is damaged and may founder.
Standard: She was floundering on the balance beam.
Non-standard: The ship is damaged and may flounder.

Flout and flaunt. One flouts a rule or law by flagrantly ignoring it. One flaunts something by showing it off.
Standard: If you've got it, flaunt it.
Standard: He continually flouted the speed limit.
Non-standard: If you've got it, flout it.
Non-standard: He continually flaunted the speed limit.

Hay and Straw

Historic and historical. In strict usage, historic describes an event of importance – one that shaped history or is likely to do so. Historical merely describes something that happened in the past.
Standard: The president made a(n) historic announcement. (The announcement was of historical importance.)
Non-standard: The office kept an archive of historic records. (The records are not necessarily of historical importance – they are simply records from the past.)

Hoard and horde. A hoard is a store or accumulation of things. A horde is a large group of people.
Standard: A horde of shoppers lined up to be the first to buy the new gizmo.
Standard: He has a hoard of discontinued rare cards.
Non-standard: Don't horde the candy, share it.
Non-standard: The hoard charged when the horns sounded.

Imply and infer. Something is implied if it is a suggestion intended by the person speaking, whereas a conclusion is inferred if it is reached by the person listening.
Standard: When Tony told me he had no money, he was implying that I should give him some.
Standard: When Tony told me he had no money, I inferred that I should give him some.
Non-standard: When Tony told me he had no money, he was inferring that I should give him some.
Non-standard: When Tony told me he had no money, I implied that I should give him some.

Infamous and Famous. To be famous is to be widely-known. Infamous is to be of exceedingly ill repute (it derives not from fame, but from infamy).
Standard: Adolf Hitler was an infamous dictator.
Standard: John Wayne was a famous actor.
Non-standard: John Wayne was an infamous actor.

Inherent and inherit. A part inherent in X is logically inseparable from X. To inherit is a verb, meaning "pass down a generation".
Standard: Risk is inherent in the stock market.
Standard: The next president inherits a legacy of mistrust and fear.
Non-standard: There is violence inherit in the system.

It's and its. It's is a contraction that replaces it is or it has (see apostrophe). Its is the possessive pronoun corresponding to it, in the same way that his corresponds to he. In standard written English, possessive nouns take an apostrophe, but possessive pronouns do not.
Standard: It's time to eat!
Standard: My cell phone has poor reception because its antenna is broken.
Standard: It's been nice getting to meet you.
Non-standard: Its good to be the king.
Non-standard: The bicycle tire had lost all it's pressure.

Lay (lay, laid, laid, laying) and lie (lie, lay, lain, lying) are often used synonymously. Lay is a transitive verb, meaning that it takes an object. "To lay something" means to place something. Lie, on the other hand, is intransitive and means to recline (and also to tell untruths, but in this case the verb is regular and causes no confusion). The distinction between these related verbs is further blurred by the fact that past tense of lie is lay. A quick test is to see if the word in question could be replaced with recline; if it can, Standard English requires lie.
Standard: I lay my husband's work clothes out for him every morning. Yesterday I decided to see if he paid attention to what I was doing, so I laid out one white sock and one black. He didn't notice!
Standard: You should not lie down right after eating a large meal. Yesterday I lay on my bed for half an hour after dinner, and suffered indigestion as a result. My wife saw me lying there and made me get up; she told me that if I had waited for a couple of hours I could have lain down in perfect comfort.
Non-standard: Is this bed comfortable when you lay on it? (Should be lie)
Non-standard: Yesterday I lied down in my office during the lunch hour. (Should be lay)
Non-standard: There was no reason for him to have laid down in the middle of the path, it unnerved me to see him laying there saying nothing. (Should be "have lain down" and "him lying there")
Non-standard: Lie the baby down, and change his diaper (Should be "lay", as "lie" is intransitive)

Levee and levy. A levee is a structure built along a river to raise the height of its banks, thereby preventing nearby land from flooding (see: dike). To levy is to impose (1) a tax, fine or other assement, or (2) a military draft; as a noun, a levy is an assessment or army thus gathered. The two words share a common root, but they are not considered interchangeable in Standard English. Because they are homophones, misuse is usually only apparent when observed in writing.
Standard: The Netherlands is well known for its elaborate system of levees.
Standard: This statute allows the state to levy a 3 % tax.
Non-standard: Recent storms have weakened the levy.

Loathe: Often used for loth or loath in phrases such as "She was loathe to accept." Loathe is used only as a verb in Standard English.

Marinate and Marinade. In Standard English, "marinade" is a noun.
Standard: The meat will taste better if you marinate it in olive oil before cooking.
Standard: Prepare the marinade by mixing vinegar and soy sauce.
Non-standard: Marinade the meat in wine for half an hour.

Me, myself and I. In a traditional prescriptive grammar, I is used only as a subject, me is used only as an object, and myself is used only as a reflexive object, that is to say when the subject is I and the object would otherwise be me.
Standard: Jim and I took the train.
Standard: He lent the books to Jim and me.
Standard: That is I in the picture.
Non-standard: Me and Jim went into town.
Non-standard: It was clear to Jim and I that the shop was shut.
Non-standard: That is me in the picture.
Myself is often used in a way that makes usage writers bristle, particularly when someone is trying to be "extra correct". Like the other reflexive pronouns, in prescriptive usage, myself should be used only when both the subject and object of the verb are the speaker, or as an emphatic pronoun (intensifier).
Standard (intensifying): I myself have seen instances of that type.
Standard (reflexive): I hurt myself. I did it to myself. I played by myself. I want to enjoy myself.
Non-standard: As for myself, I prefer the red. (Just use me here)
Non-standard: He is an American like myself. (Just use me)
Non-standard: He gave the paper to Jim and myself. (Just use me)
Non-standard: My wife and myself are not happy with all the development going on in town. (Just use I)

Mitigate and militate. To mitigate is to make something milder. To militate is to fight or exert pressure for something to happen or not to happen.
Standard: The seriousness of your crime was mitigated by the provocation you were under
Standard: Over-protective practices in this factory militate against increased efficiency
Non-standard: Over-protective practices in this factory mitigate against increased efficiency


Of and have. In some dialects spoken English, of and the contracted form of have, 've, sound somewhat alike. However, in standard written English, they aren't interchangeable.
Standard: Susan would have stopped to eat, but she was running late.
Standard: You could've warned me!
Non-standard: I should of known that the store would be closed. (Should be "I should've known")

Redundant does not mean useless or unable to perform its function. It means that there is an excess of something, that something is "surplus to requirements" and no longer needed, or that it is obsolete.
Standard: A new pill that will instantly cure any illness has made antibiotics redundant. (Antibiotics could still be used to cure illnesses, but they are no longer needed because a better pill has been invented)
Standard: The week before Christmas, the company made 75 workers redundant.
Non-standard: Over-use of antibiotics risks making them redundant. (This should read: over-use of antibiotics risks making them worthless)

Set and sit.

Shrink and shirk. To shirk means "to consistently avoid", "to neglect", "to be too afraid to engage". To shrink means "to contract", "to become physically smaller in size"; also to shrink away means "to suddenly jerk away from something in horror". However, to shrink from may also mean "to hesitate or show reluctance toward".
Standard: I won't shirk discussion.
Standard: I won't shrink from discussion.
Standard: She shrank away from me.
Non-standard: I won't shrink discussion.
Non-standard: I won't shirk from discussion.

Sight and site and cite. A site is a place; a sight is something seen. To cite is to quote or list as a source.
Standard: You're a sight for sore eyes.
Standard: I literally found lots of sites on the internet---I was looking at a tourist site for Rome.
Standard: Please cite the sources you used in your essay.
Non-standard: I found lots of sights on the internet.
Non-standard: I will site the book I saw the statistics in.

Temblor and trembler. A temblor is an earthquake. A trembler is something that trembles.

Than and then. Than is a grammatical particle and preposition associated with comparatives, whereas then is an adverb and a noun. When spoken, the two words are usually homophones because they are function words with reduced vowels, and this may cause speakers to confuse them.
Standard: I like pizza more than lasagne.
Standard: We ate dinner, then went to the movies.
Non-standard: You're a better person then me.

There, their and they're. While they can all sound the same in some dialects, in standard written English they all have separate, definite meanings, and are not interchangeable. There refers to the location of something. Their means "belonging to them". They're is a contraction of "They are".
Standard: Since they're all coming to the restaurant for their dinner, we'll meet them there.

There's, where's, etc. A common spoken mistake is using a singular contraction when it should be plural in words like "there's" and "where's."
Standard: Where's the car?
Non-standard: There's many types of cars. (Should be There're)
You're, your, yore and ewer. While they sound the same in many dialects, in standard written English they all have separate meanings. You're is a contraction for "you are", and your is a possessive pronoun meaning "belonging to you". When in doubt, just see whether you can logically expand it to "you are". The third homonym, yore, is an archaism meaning in the distant past, and is almost always used in the phrase "in days of yore". The fourth is the name of a once common piece of household equipment made obsolete by indoor plumbing: the large jug holding washing water.
Standard: When driving, always wear your seatbelt.
Standard: If you're going out, please be home by ten o'clock.
Non-standard: You're mother called this morning.
Non-standard: Your the first person to notice my new haircut today!

Won't and wont (usually pronounced like want, though in British English the two words are usually pronounced the same). Won't is a contraction for "will not", while wont is a less frequently used and completely different word: as an adjective it means accustomed or inclined to.
Standard: He won't let me drive his car.
Standard: He spent the morning reading, as he was wont to do.
Non-standard: I wont need to go to the supermarket after all.