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.: See Usage note at the current entry.
the simple past tense and past participle of nonplus.
- Sometimes non·plused .
There are several theories about how this contradictory second meaning came into being. One explanation is the analysis of nonplussed as non- “not” + plussed, interpreted as “not puzzled, perplexed, bothered, or impressed,” possibly by analogy with other words that have a negative prefix and similar meaning, such as unfazed and indifferent, and perhaps influenced by nonchalant. However, plussed has no meaning in English, and the non at the beginning is not in fact the common English negative prefix non- found in such words as nonalcoholic or nonexistent. Interestingly, the adjective nonplussed was formed from the less common verb nonplus “to puzzle or perplex,” which was originally a noun meaning “a state of utter perplexity,” and this noun was borrowed from the Latin phrase nōn plūs “not more; no further.” In other words, a state of perplexity is one in which the person can think of no more to say or do.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use nonplussed in a sentence
The prisoner was evidently nonplused, but it was only for a moment.Scotch Wit and Humor | W. H. (Walter Henry) Howe
“I will,” promised Tom, somewhat nonplused at the outcome of the affair.The Winning Touchdown | Lester Chadwick
And for a moment she stared at the scene, nonplused, discomfited.The White Moll | Frank L. Packard
Something had gone wrong in the engine room, and the engineer was nonplused."Say Fellows--" | Wade C. Smith
Mr. Reginald Kent looked rather nonplused and Mr. Tucker handed me his gun to hold while he rolled in the leaves for very joy.At Boarding School with the Tucker Twins | Nell Speed