Another word for certain
assured, sure, positive, questionless, satisfied, self-confident, undoubting, unwavering, believing, secure, untroubled, unconcerned, undisturbed, unperturbed, convinced, assertive, cocksure; see also calm 1, confident 2.
indisputable, unquestionable, assured, positive, real, true, genuine, plain, clear, undoubted, indubitable, guaranteed, unmistakable, unassailable, sure, incontrovertible, undeniable, definite, supreme, unqualified, infallible, undisputed, unerring, sound, reliable, trustworthy, evident, conclusive, decisive, unambiguous, authoritative, irrefutable, unconditional, incontestable, unquestioned, absolute, unequivocal, inescapable, in the bag*, on ice*; see also accurate 1.
Specific but not named
special, marked, specified, defined, one, some, a few, a couple, several, appreciable, upwards of, regular, particular, singular, especial, precise, specific, express; see also definite 1, individual 1, special 1.
certain usually suggests conviction based on specific grounds or evidence this letter makes me certain of his innocence; suresuggests merely an absence of doubt or hesitancy I'm sure you don't mean it; confident stresses the firmness of one's certainty or sureness, esp. in some expectation she's confident she'll win; positive suggests unshakable confidence, esp. in the correctness of one's opinions or conclusions, sometimes to the point of dogmatism he's too positive in his beliefsbe certain
be sure, have confidence, feel sure, be confident, have no doubt, make certain; see also know 1.
Another word for certainadjective
In a definite and final form; not likely to change:firm1, fixed, flat, set1. See change
Bound to happen:inescapable, inevitable, sure, unavoidable. See certain
Established beyond a doubt:hard, inarguable, incontestable, incontrovertible, indisputable, indubitable, irrefutable, positive, sure, unassailable, undeniable, undisputable, unquestionable. See certain, true
Known positively:definite, positive, sure. Idiom: for certain. See certain
Such as could not possibly fail or disappoint:infallible, secure, sure, unerring, unfailing. (Informal) sure-fire. See certain
Having no doubt:assured, confident, positive, sure, undoubting. See certain