nonplused

non·plus  (nn-pls)

tr.v. non·plussed also non·plused, non·plus·sing also non·plus·ing, non·plus·ses also non·plus·es

To put at a loss as to what to think, say, or do; bewilder.

n.

A state of perplexity, confusion, or bewilderment.

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[From Latin nn pls, no more : nn, not; see non- + pls, more; see pel-¹ in Indo-European roots.]

Thesaurus

Adj.

1.

nonplused - filled with bewilderment; "at a loss to understand those remarks"; "puzzled that she left without saying goodbye" at a loss, nonplussed, puzzled perplexed - full of difficulty or confusion or bewilderment; "perplexed language"; "perplexed state of the world"