certain

The word “certain” means completely confident that something is true. In plain terms, sure or definite — either about a belief, an outcome, or referring to something specific but unspecified.

“Certain” is pronounced SUR-tuhn (/ˈsɝ.tən/ in IPA).

Here is “certain” used in a sentence: “She was certain she had locked the door.”

Words with a similar meaning to “certain” include assured, clear, confident, doubtless, definite and positive.

The opposite of “certain” — its antonyms — are uncertain, impossible, incidental and particular specific.

Depending on how it is used, “certain” can be an adjective and a det.

The word “certain” comes from Latin. From Old French certain, from a Latin root related to certus ("fixed, settled, sure").

“Certain” is a very common word in modern English, usually learned at around the A2 level.

The two are very close, and often interchangeable — both mean confident that something is true. 'Certain' tends to sound a little more formal and absolute, suggesting no room for doubt at all. 'Sure' is more casual and everyday. You might feel sure of an answer, but certain of a proven fact.

The main opposites are uncertain, unsure, and doubtful — words describing a lack of confidence that something is true. If you are certain, you have no doubt; if you are uncertain, you are still weighing the possibilities. 'Doubtful' and 'in two minds' capture that same feeling of not yet being convinced.

Yes. Besides meaning fully confident, 'certain' can point to something particular but unnamed, as in 'a certain person called' or 'under certain conditions.' Here it hints at a specific thing without spelling it out. The same word can also mean guaranteed to happen, as in 'certain victory.' Context makes clear which sense applies.