Entry Word: certain

Function: adjective

Meaning: 1 known but not named <a certain person told me that today is your birthday>

Synonyms anonymous, one, some, unidentified, unnamed, unspecified

Related Words particular, specific

Near Antonyms known, named, specified

2 having or showing a mind free from doubt <Iʼm certain that theyʼll arrive on time>

Synonyms assured, clear, cocksure, confident, doubtless, positive, sanguine, sure

Related Words self-assured, self-conceited, self-confident; decisive, resolute, unfaltering, unhesitating, unwavering

Near Antonyms hesitant, indecisive, wavering; diffident, unassuming

Antonyms doubtful, dubious, uncertain, unsure

3 having been established and usually not subject to change <a certain percentage of the profits will go to charity> — see fixed 1
4 impossible to avoid or evade <as he got older, the athlete began to feel the certain effects of the aging process on his body> — see inevitable
5 not likely to fail <chicken soup is grandmaʼs certain cure for pretty much whatever ails you> — see infallible 2