- completely puzzled or perplexed by something unexpected: She blows a hole in the wall and escapes, and the nonplussed aliens are left wondering what happened.
- not dismayed; indifferent or unexcited; calm: I hadn’t yet told my girlfriend I was leaving—I didn't want to risk being crushed by a nonplussed response to the news.
- the simple past tense and past participle of nonplus.
