Synonyms and related words :
a stranger to, aback, asleep, blind to, caught napping, dead to, deaf to, heedless, ignorant, impercipient, in ignorance of, incognizant, inexpectant, inobservant, insensible, insensible to, lost to, mindless, napping, nonconceiving, nonexpectant, not with it, oblivious, out of it, short, sudden, suddenly, unacquainted, unadmonished, unadvised, unanticipatedly, unanticipating, unanticipative, unaware of, unconscious, unconscious of, unenlightened, unexpectedly, unexpecting, unfamiliar, unforewarned, unguessing, unhearing, uninformed, uninsightful, uninstructed, unknowing, unmindful, unmindful of, unperceiving, unprehensive, unprepared, unready, unrealizing, unseeing, unsuspecting, unwarned, unwitting, witless