certain

Feeling no doubt that something is true, or known to be true without doubt.

• I am certain she is right.
• Are you certain about the date?
• Only one fact was certain: the door had been locked.

How to use it: be certain of/about something (Are you certain of the answer?); be certain that… (I am certain that she told the truth.)

Similar words: sure, confident, definite

Opposites: uncertain, doubtful

Common phrases: certain of something, absolutely certain, certain that, quite certain

Definitely going to happen.

• Their victory seemed certain.
• You are certain to enjoy the show.
• Without help, the climbers faced certain death.

How to use it: be certain to do something (Prices are certain to rise.); be certain of something (The team is certain of a place in the final.); it is certain that… (It is certain that the event will attract a crowd.)

Similar words: guaranteed, inevitable, assured

Opposites: uncertain

Common phrases: certain victory, certain death, certain to win

In “make certain”, to check that something is true or arrange for something to happen as needed.

• Make certain the door is locked.
• She called to make certain of the time.
• We made certain that everyone had a seat.

How to use it: make certain of something (Make certain of the address before you leave.); make certain that… (Make certain that all the windows are closed.)

Common phrases: make certain, make certain of, make certain that

Fixed or decided, rather than changing or left unknown.

• The payments fall due at certain intervals.
• The agreement sets a certain period for repayment.
• A certain amount was payable each month under the old contract.

Similar words: fixed, definite, determinate

Opposites: variable, indeterminate

Common phrases: certain intervals, certain period, certain amount

Some particular people or things, without saying exactly which ones.

• Certain foods make me feel ill.
• The rule applies only in certain cases.
• A certain person has been asking about you.

How to use it: certain + plural noun (Certain plants need very little water.); a certain + singular noun (A certain neighbour keeps complaining.)

Similar words: some, particular

Common phrases: certain people, certain conditions, a certain person, certain details

Some people or things from a group, without saying exactly which ones.

• Certain of them refused to sign.
• Certain of the documents have been lost.
• The witnesses gave statements, of which certain were later withdrawn.

How to use it: certain of + plural noun/pronoun (Certain of the members opposed the proposal.)

Similar words: some

Common phrases: certain of them, certain of us, certain among them