Being correct in your writing and speaking means choosing words that correctly communicate what you mean. That seems easy enough, but there are certain words that confuse even the best writers. The following list describes some commonly confused words.
Advice, advise: Advice means a recommendation on what to do. (I have some advice on navigating the subway.) Advise means to suggest or guide. (I advise you to avoid driving in England.)
Affect, effect: Affect is a verb meaning to change or influence. (How will the policy affect the itinerary?) Effect as a verb means to bring about, and, as a noun, it means result or outcome. (The policy will have an interesting effect.)
Complement, compliment:Complement means to complete. (The shore excursion complements the cruise.) Compliment means to flatter or praise. (The passenger complimented the captain on such a fine cruise.)
Convince, persuade: Convince and persuade both mean to move a person to believe your argument or agree with you. It’s what comes after the word that makes the difference. A person may be convinced that or convinced of something. (I convinced my client that the all-inclusive resort would meet his family’s needs.) But the person must be persuaded to do something. (I persuaded Mary to book her cruise before the rates increased.)
Could’ve, could of: Could’ve means could have. (I could’ve been a contender.) Could of is not proper; a preposition cannot serve as a verb.
Disinterested, uninterested: Disinterested means impartial. (Let’s ask a disinterested party which is better: a taxi or a bus.) Uninterested means not interested. (Bob is uninterested in sightseeing.)
Imply, infer: Imply means to suggest indirectly. (The concierge implied that the restaurant would be too expensive.) Infer means to draw a conclusion. (I inferred she thought we were stingy.)
Irregardless, regardless: Irregardless is an improper version of regardless and is not a word. Regardless means despite everything. (I am going ahead with our plans regardless.)
Its, it’s: It’s is a contraction for it is or it has. Its is a possessive pronoun meaning of it or belonging to it. If you can replace it’s in a sentence with it is or it has, then the correct word is it’s; otherwise, the word is its. There is no such word as its’.
Less, fewer: Less means things that can’t be counted individually (Ponds generally contain less water than lakes.) Fewer means things that can be counted. (Fewer than 15 people attended the docent’s lecture.)
Than, then: Than is used with comparisons. (I would rather eat out than order room service.) Then means next. (I went to the museum then to the mosque.)
That, which: Use that with essential clauses. Don’t put a comma before it. (The hurricane that everyone remembers is Katrina.) Use which with nonessential clauses. You must use a comma before it. (Hurricane Katrina, which is a storm everyone remembers, caused much devastation.) Notice the title of this column is “Words That Confuse.”
Their, there, they’re: Their means belonging to them. (Clients are loyal to their travel agents.) There means a location. (The dock is there, just past the bait shop.) They’re means they are. (They’re ready to depart immediately.)
Your, you’re: Your means belonging to you. You’re means you are. (You’re going to forget your passport unless you put it in your purse.)
This information was taken from the Business Writing Skills module in The Travel Institute’s Certified Travel Associate program.