Nonplussed

//nɒnˈplʌst// adj, verb, slang

adj, verb, slang ·Common ·High school level

Definitions

Verb
  1. 1
    simple past and past participle of nonplus form-of, participle, past
Adjective
  1. 1
    Unsure how to act or respond; bewildered, perplexed.

    "[N]ote the honeſt Quaker vvas nonpluſſed, and greatly ſurprized at that Queſtion."

  2. 2
    Unaffected, unfazed; unimpressed. US, informal, nonstandard

    ""I regard Dean [W. P.] Baddeley's gambling activities with embarrassment and dismay," said Anglican dean of Melbourne S. Barton Babbage. […] The Rev. Baddeley remained nonplussed. "I don't intend to make a habit of going to the races but I feel clergymen should mix as our Lord did with all walks of life," Dr. Baddeley said."

Adjective
  1. 1
    filled with bewilderment wordnet

Synonyms

All synonyms
confoundedperplexedabashedabashedaddle-patedaddled

Example

More examples

"She was completely nonplussed by his unexpected behavior."

Etymology

From nonplus (“state of bewilderment or perplexity”, noun) or nonplus (“to bewilder or perplex (someone)”, verb) + -ed (suffix forming adjectives, and the past tense and past participle forms of verbs). Nonplus (noun) is derived from Latin nōn plūs (“no further, no more”), from nōn (“not”) + plūs (“additionally, more; further”) (ultimately from Proto-Indo-European *pleh₁- (“to fill”)). The etymological sense is similar to being left speechless as a result of confusion: the nonplussed person can say or do “no more”. Adjective sense 2 (“unaffected”) is probably from a misinterpretation of the first element of the word as the prefix non- meaning “not”.

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.