• WordNet 3.6
    • v nonplus 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"
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Webster's Revised Unabridged Dictionary
    • n Nonplus A state or condition which baffles reason or confounds judgment; insuperable difficulty; inability to proceed or decide; puzzle; quandary. "Both of them are a perfect nonplus and baffle to all human understanding."
    • v. t Nonplus 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."
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Century Dictionary and Cyclopedia
    • n nonplus A state in which one is unable to proceed or decide; a state of perplexity; a puzzled condition; inability to say or do more; puzzle: usually in the phrase at or to a nonplus.
    • nonplus To perplex; puzzle; confound; put to a standstill; stop by embarrassment.
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Chambers's Twentieth Century Dictionary
    • n Nonplus non′plus a state in which no more can be done or said: great difficulty
    • v.t Nonplus to perplex completely, to puzzle:—pr.p. non′plussing; pa.t. and pa.p. non′plussed
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Webster's Revised Unabridged Dictionary
L. non, not + plus, more, further. See Plural


In literature:

He looked at her for a nonplused moment, at her brown arms bent over her shaken bosom, at the shield of her broken hat.
"The Emigrant Trail" by Geraldine Bonner
For once in his stormy life he was nonplused.
"The Stowaway Girl" by Louis Tracy
I could see from Mr. Royce's face how absolutely nonplused he was.
"The Holladay Case" by Burton E. Stevenson
Marie sat, nonplused, staring at the Champion's defiant figure.
"Betty Wales Senior" by Margaret Warde
It seems, however, that, in common with myself, your numerous correspondents are quite at a nonplus.
"Notes and Queries, No. 179. Saturday, April 2, 1853." by Various
Peter Polk was nonplused.
"Randy of the River" by Horatio Alger Jr.
Vanslyperken was at a nonplus.
"Snarley-yow" by Frederick Marryat
Mephistopheles at a nonplus, 62.
"The Biglow Papers" by James Russell Lowell
They were put to a nonplus, and summoned the Devil to their relief.
"A Budget of Paradoxes, Volume I (of II)" by Augustus De Morgan
Delia was completely nonplused.
"The Governess" by Julie M. Lippmann

In news:

A Time Warner Cable customer was surprised to find a charge for 17 adult titles on her bill and nonplused when a service rep scoffed at her complaint.