verb
1.
to cause to be at a total loss as to how to act or decide
was totally nonplussed by the economic problems
Synonyms: beat, buffalo, get, stick, stump; compare puzzle
Related Word: baffle, frustrate, stymie, thwart; confound, perplex; mystify; dumbfound; overcome, throw; paralyze; confuse, flurry, fluster, muddle, rattle
Idioms: put ( or drive) to one's wit's end, put up a tree ( or stump), throw on one's beam end
2.
Synonyms: stagger 5, boggle, dumbfound
Related Word: faze, rattle; baffle, balk, frustrate