With English as tricky as it is—full of homonyms, homophones, homographs, and other oddities—it’s no wonder mistakes occur even in communication from the most trusted sources. On an off day, anyone can type hear for here or to for too.

These errors may cause momentary embarrassment, but they tend to be both easily caught with a good proofread and quickly forgotten when they do slip by. More harmful are mistakes that indicate lack of knowledge rather than a lapse in attention. Misuse of words (rather than mistyping) can make you look foolish and even damage your reputation.

To help you avoid such errors, we’ve compiled a list of words that are commonly confused in professional writing. Take a moment to see whether you consistently use these words correctly. If you do, congratulations—you’re ahead of many of your colleagues.

Misuse of words can make you look foolish and even damage your reputation.

Adverse, averse. Adverse means unfavorable or detrimental; averse means opposed.

He was averse to attending meetings because of the adverse effect they had on his mood.

Affect, effect. In nearly all situations, affect is the word to choose if you’re looking for a verb; effect is a noun. (Affect as a noun is reserved to describe emotion or its expression—not a common use in business writing.)

The effect of good writing is to make the writer sound informed. Good writing can affect your business in a positive way.

Alternate, alternative. Alternate means by turns; alternative means offering a choice. (Yes, all of those “Alternate route” signs on the road are incorrect.)

The alternative to running every meeting yourself is to alternate between yourself and another executive.

Appraise, apprise. To appraise is to assess or set a price for something. To apprise is to inform.

He apprised his supervisor that the painting had been appraised at a high price.

Classic, classical. Use classic to mean high-quality or standard-setting; classical means pertaining to 18th and 19th century orchestral music or to ancient Greece or Rome.

The ad for our new product is classic; the use of classical music gave it just the right level of sophistication.

Complacent, complaisant. Although they come from the same root, these words have conflicting meanings: a complacent person is pleased with himself to the point of failing to notice a problem, while a complaisant person works to please others.

We must not be complacent about staff development; we need to work to ensure that all staff members are complaisant in dealing with customers.

Compose, comprise. Comprise means to contain or include, while compose is to be a part of something. The key here is to remember that comprised of is incorrect.

The conference is composed of three tracks; each track comprises six presentations.

Council, counsel. A council is an administrative group or assembly. Counsel is advice or a verb meaning to give advice, unless you’re referring to a legal advisor.

The town council member counseled against spending more on business development.

Discreet, discrete. To be discreet is to show prudence, particularly about a delicate matter. Discrete means separate or distinct.

In business it’s important to be discreet about using social media, including discrete personal accounts that may reflect on the organization.

Disinterested, uninterested. If you want to say that someone has no interest in something, use uninterested. Reserve disinterested to mean impartial or unbiased.

A judge should always be disinterested but never uninterested in the court’s cases.

e.g., i.e. Both terms are Latin abbreviations: e.g., short for exempli gratia, means “for example”; i.e., short for id est, means “that is.”

To be effective, our communications (e.g., through our website, newsletter, and advertisements) must be accurate (i.e., have correct information presented without mistakes).

Eminent, imminent. A person of importance is eminent; an event that is about to happen is imminent.

The arrival of our most eminent Board member is imminent.

Ensure, insure. To ensure is to make sure of; to insure is to indemnify against loss, e.g., through an insurance policy.

We need to ensure that the policy to insure our warehouse is up to date.

Everyday, every day. Everyday is an adjective describing something ordinary or occurring daily; use every day when you mean “each day.”

Our sales increase every day that we have a special, although our everyday prices are just as good.

Faze, phase. To faze is to disturb; a phase is a stage or aspect of development.

Differences in revenue across the phases of the sales cycle don’t faze him.

Flaunt, flout. This pair is widely confused even in the press, but their meanings are very different. To flaunt is to show off; to flout is to disregard or treat with disdain.

She flouted convention by flaunting her wealth at the trade show.

Flounder, founder. This is another pair that seems more commonly confused than not. Both words indicate difficulty, but of different types and degrees. Flounder means to struggle or flail about; founder means to sink, either literally (as when a ship goes down) or figuratively (as in to fail completely).

Executives floundered while trying to figure out how to keep the companying from foundering.

Forego, forgo. Forego means to go before; forgo means to do without. (To keep them straight, think of the “fore” in both forego and before.)

We will have to forgo serving breakfast at the meeting because of the foregoing session.

Imply, infer. To imply is to suggest something without stating it explicitly; to infer is to deduce or surmise. Simply put, a speaker implies, a listener infers.

John implied that sales were slipping because of the latest marketing campaign; we inferred that he wanted a new strategy.

Led, lead. The common mistake here is to write lead instead of led when using the past tense for the verb meaning to lead the way—probably because of confusion with the metal lead.

Our organization led the way for others to come, and we still lead the field with our services.

See this article for more tips on language use.

Lose, loose. Lose is the word that indicates failing to win; loose (think: rhymes with moose) means not tight or, as a verb, to unleash.

If we lose this account, we will need to let loose some of our staff.

Militate, mitigate. Militate means to influence or weigh against; mitigate means to moderate or lessen in severity. The phrase mitigate against, while frequently seen, is incorrect.

John thought Lisa’s lack of experience might militate against her promotion, but her popularity among clients mitigated this impression.

Peak, pique. Use pique to mean resentment or, as a verb, to excite interest. Peak means the top or highest level.

The newsletter item piqued the interest of hundreds of readers, making it a peak performer for us.

Prescribe, proscribe. While often confused, these words are nearly opposite in meaning. Prescribe means to recommend or set down as a rule; proscribe means to forbid or denounce.

To create a great website, we would prescribe putting key information up front; in contrast, we would proscribe adding too many fonts, images, and colors.

Than, then. Use than when you are making a comparison. Then indicates time or order. (To remember which is which, think: When? Then.)

We would rather win customers with great service than with empty marketing; then we can be sure they’ll remain loyal.

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