Synonyms and related words :
agnostic, ambiguous, balbutient, bashful, boggling, capricious, cautious, chancy, changeable, demurring, dicey, diffident, doubting, equivocal, erratic, faltering, fickle, halting, hesitant, incalculable, indecisive, indemonstrable, irresolute, jibbing, modest, polysemous, qualmish, scrupling, scrupulous, shilly-shallying, shrinking, shy, skeptical, squeamish, stammering, sticking, stickling, straining, stumbling, stuttering, tentative, timid, touch-and-go, unaccountable, uncertain, unconfirmable, unconvinced, undivinable, unforeseeable, unpersuaded, unpredictable, unprovable, unsure, unverifiable, variable, wavering, whimsical