nonplussed

faced with difficulty or uncertainty about what to say, think, or do the self-possessed actress seemed uncharacteristically nonplussed after the director's harsh appraisal of her performance Synonyms baffled, confounded, hard-pressed, hard put (also nonplused), perplexedRelated Words bewildered, confused, disconcerted, fazed; embarrassed, flustered, put outNear Antonyms undaunted, unfazed; composed, untroubled