Synonyms and related words :
abulic, adrift, afloat, afraid, alternating, amorphous, anemic, asthenic, bloodless, capricious, changeable, changeful, chicken, cowardly, craven, dastardly, debilitated, desultory, deviable, dizzy, drooping, droopy, dull, eccentric, effete, emasculate, erratic, etiolated, faint, fainthearted, faintish, fast and loose, fearful, feeble, feebleminded, fickle, fitful, flabby, flaccid, flickering, flighty, flitting, floppy, fluctuating, forceless, frail, freakish, giddy, gone, gutless, imbecile, impetuous, impotent, impulsive, inadequate, inconsistent, inconstant, indecisive, ineffective, ineffectual, infirm, invertebrate, irregular, irresolute, irresponsible, languid, languorous, lily-livered, limber, limp, listless, lustless, marrowless, mazy, mercurial, moody, nerveless, pithless, pliable, pooped, powerless, pusillanimous, rambling, restless, roving, rubbery, sapless, scatterbrained, shapeless, shifting, shifty, shuffling, sinewless, slack, soft, spasmodic, spiritless, squeamish, strengthless, timid, timorous, unaccountable, uncertain, uncontrolled, undependable, undisciplined, unfixed, unhardened, unnerved, unpredictable, unreliable, unrestrained, unsettled, unstable, unstable as water, unstaid, unsteadfast, unsteady, unstrung, vacillating, vagrant, variable, vicissitudinary, vicissitudinous, volatile, wandering, wanton, wavering, wavery, wavy, wayward, weak, weak-kneed, weak-minded, weak-willed, weakly, whimsical, white-livered, wishy-washy, yellow