nervous
agitated, anxious, apprehensive, edgy, excitable, fearful, fidgety, flustered, hesitant, highly strung, hyper (informal) hysterical, jittery (informal) jumpy, nervy (Brit. informal) neurotic, on edge, ruffled, shaky, tense, timid, timorous, twitchy (informal) uneasy, uptight (informal) weak, wired (slang) worried, bold, calm, confident, constant, cool, equable, even, laid-back (informal) peaceful, relaxed, steady, together (slang) unfazed (informal)
nervous breakdown
breakdown, collapse, crack-up (informal) nervous disorder, neurasthenia (obsolete)