Longman Dictionary of Contemporary English
The Collaborative International Dictionary
Nonplus \Non"plus`\, v. t. [imp. & p. p. Nonplusedor Nonplussed; p. pr. & vb. n. Nonplusing or Nonplussing.] To puzzle; to confound; to perplex; to cause to stop by embarrassment.
He has been nonplused by Mr. Dry's desiring him to tell
what it was that he endeavored to prove.
--Spectator.
Douglas Harper's Etymology Dictionary
c.1600, past participle adjective from nonplus.
Wiktionary
1 bewildered; unsure how to respond or act. 2 (context proscribed US informal English) unfazed, unaffected, or unimpressed. v
(en-past of: nonplus)
WordNet
v. be a mystery or bewildering to; "This beats me!"; "Got me--I don't know the answer!"; "a vexing problem"; "This question really stuck me" [syn: perplex, vex, stick, get, puzzle, mystify, baffle, beat, pose, bewilder, flummox, stupefy, gravel, amaze, dumbfound]
[also: nonplussing, nonplusses, nonplussed]
See nonplus
Usage examples of "nonplussed".
Flustered, she walked into the kitchen, nonplussed by her rapid pulse, a sinking sensation, a feeling of weakness.
Even Smith, accustomed to storm, was nonplussed at the suddenness of the attack upon him.
For a moment she was nonplussed, then she opened the gate and went in.
The priest was still off on errands around the city, and after a few walks about the green to assuage their consciences, all had returned, nonplussed, to intelligence headquarters.
To say that Bertram was now definitely nonplussed would be but to state the simple truth.
She was so shocked, so nonplussed, at the scene that she doubted she could have said a word.
While he stood nonplussed, looking after them, Miss Hastings glided to his side in a matter of course way.
Ulla was waiting, just as she expected, and she dismissed the nonplussed girl.
With the appearance of the first dish upon the table that night the boy was very frankly nonplussed at the array of implements upon each side of his plate, placed there for him to manipulate.
And henceforth, won over by that feast of colours, she would have declared it all capital if he would only have condescended to finish his work a little more, and if she had not remained nonplussed now and then before a mauve ground or a blue tree, which upset all her preconceived notions of colour.
Then, when Moon Frost landed, momentarily nonplussed at not finding her prey where it should have been, Firekeeper swung behind her and launched herself astride.