Synonyms and related words :
adrift, afloat, alternating, amorphous, capricious, changeable, changeful, coquettish, dangerous, desultory, deviable, dizzy, doubtful, dubious, eccentric, erratic, faddish, fast and loose, fickle, fitful, flickering, flighty, flirtatious, flitting, fluctuating, fly-by-night, freakish, giddy, hazardous, impetuous, impulsive, inconsistent, inconstant, indecisive, infirm, insecure, insubstantial, irregular, irresolute, irresponsible, light, mazy, mercurial, moody, perilous, precarious, provisional, quicksilver, rambling, restless, risky, rocky, roving, scatterbrained, shaky, shapeless, shifting, shifty, shuffling, skittish, slippery, spasmodic, spineless, temporary, tentative, ticklish, tottery, toying, treacherous, tricky, trustless, unaccountable, uncertain, uncontrolled, undisciplined, unfaithworthy, unfixed, unhealthy, unpredictable, unreliable, unrestrained, unsafe, unsettled, unsolid, unsound, unstable, unstable as water, unstaid, unsteadfast, unsteady, unsubstantial, unsure, untrustworthy, untrusty, vacillating, vagrant, variable, versatile, vicissitudinary, vicissitudinous, volatile, wandering, wanton, wavering, wavery, wavy, wayward, whimsical, wishy-washy