1. (a.) Not certain; not having certain knowledge; not assured in mind; distrustful.

2. (a.) Irresolute; inconsonant; variable; untrustworthy; as, an uncertain person; an uncertain breeze.

3. (a.) Questionable; equivocal; indefinite; problematical.

4. (a.) Not sure; liable to fall or err; fallible.

5. (v.) To make uncertain.

Pyrrhonic adrift afloat agnostic alternating ambiguous ambitendent ambivalent amorphous amphibological amphibolous at a loss at loose ends blear bleared bleary blurred blurry broken capricious careening catchy chancy changeable changeful choppy confused dark desultory deviable deviative dicey dim disconnected discontinuous distrustful dizzy double-minded doubtful doubting dubious eccentric enigmatic equivocal equivocatory erratic faint fast and loose feeble fence-sitting fence-straddling fickle filmy fitful flickering flighty flitting fluctuating foggy freakish from Missouri fuzzy giddy guttering half-seen half-visible halting hazardous hazy herky-jerky hesitant hesitating heteroclite iffy ill-defined immethodical impetuous impulsive in doubt incalculable inconsistent inconspicuous inconstant indecisive indefinite indemonstrable indistinct indistinguishable infirm infirm of purpose insecure intermittent intermitting ironic irregular irresolute irresolved irresponsible jerky leery low-profile lurching mazy mercurial merely glimpsed mistrustful mistrusting misty moody mugwumpian mugwumpish multivocal mutable mysterious nonuniform obscure of two minds out of focus pale patchy polysemantic polysemous protean questionable questioning rambling restless risky rocky rough roving scatterbrained scrappy scrupulous semivisible shadowy shaky shapeless shifting shifty shuffling shy skeptical snatchy spasmatic spasmic spasmodic spastic speculative spineless sporadic spotty staggering suspecting suspicious tottery touch-and-go treacherous unaccountable unclear unconfirmable uncontrolled unconvinced undecided undefined undependable undetermined undisciplined undivinable unequal uneven unfixed unforeseeable unhealthy unmethodical unmetrical unpersuaded unplain unpredictable unprovable unrecognizable unregular unreliable unresolved unrestrained unrhythmical unsafe unsettled unsound unstable unstable as water unstaid unsteadfast unsteady unsure unsystematic untrusting untrustworthy unverifiable vacillating vagrant vague variable veering vicissitudinary vicissitudinous volatile wandering wanton wary wavering wavery wavy wayward weak whimsical wishy-washy wobbling wobbly