Antonyms for uncertain:
unchanging, constant, trustworthy, predestinate, dependable, sure, indisputable, unquestionable, stable, destined, steady, invariable, foreordained, changeless, predestined, sanguine, assured, certain, trusty, definite, stationary, unchangeable, in for, tried, secure, tried and true, resolved, doomed, determined, safe, indubitable, fated, settled, bound, true, reliable, clear, decisive, sure as shooting, sealed.
Synonyms for uncertain:
indeterminable, coy, anonymous, alterable, irregular, unforeseeable, unexplained, unidentified, unrecorded, unclear, chicken-and-egg, unidentifiable, bashful, unheeded, dubitable, undisclosed, misunderstood, unknown, inconceivable, unheard, unremarked, unfamiliar, dogmatic, strange, undiscovered, clouded, inhibited, dangerous, unanswered, unknowable, demure, unsuspected, unacknowledged, unexplored, incognito, introverted, contested, problematical, not really, unspecified, inexplicit, fallible, Mootable, unrecognized, questioning, inferiority complex, underground, undetermined.
mercurial, mousy, unheralded, fishy, arbitrary, nebulous, inconstant, private, exceptionable, shaky, finely, unpredictable, modestly, nameless, invisible, hidden, inferior, unaccounted-for, unsolved, awkwardly.
at issue (adjective)
doubtful, changeable (adjective)
dubious, incalculable, risky, indistinct, inconstant, insecure, up in the air, erratic, unpredictable, conjectural, hesitant, undecided, indefinite, ambiguous, unclear, chancy, questionable, unforeseeable, precarious, irresolute, undetermined, unsure, vacillating, unresolved, vague, ambivalent, unsettled, irregular, unreliable, iffy, variable, speculative, indeterminate.
shy, vacillating, tentative, indecisive, inconsistent, undependable, fly-by-night, unwilling, yellow, weak, changeable, watery, unsure, insipid, impulsive, shifty, unresolved, dillydallying, capricious, spineless, halfhearted, ambivalent, Flitting, erratic, shrinking, fickle, infirm, irresponsible, irresolute, Shilly-shally, double-minded, undecided, hesitant, volatile.
moot, precarious, tentative, debatable, arguable, unconvinced, disputable, ambivalent, contestable, changeable, controversial, undecided, mysterious, questionable, intangible, deniable, insecure, vague, unsure, confused.
up in the air (adjective)
Sense 2 (noun)
Sense 4 (noun)
Sense 5 (noun)
Sense 6 (noun)
Sense 7 (noun)
Sense 9 (noun)
Sense 10 (noun)
unsettled, unsure, iffy, flukey, undependable, insecure, ambivalent, groping, hesitant, unreliable, fluky, incertain, unsealed, chancy, dubious, contingent, changeable, indefinite, unsafe, ambiguous, doubtful, variable, up in the air.