Nonplus

n.	1.	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. - South.
v. t.	1.	To puzzle; to confound; to perplex; to cause to stop by embarrassment. [imp. & p. p. Nonplused or Nonplussed; p. pr. & vb. n. Nonplusing or Nonplussing.] He has been nonplused by Mr. Dry's desiring him to tell what it was that he endeavored to prove. - Spectator.

Verb

1.

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" Synonyms: bewilder, dumbfound, flummox, baffle, mystify, perplex, puzzle, stupefy, amaze, gravel, vex, pose, stick, beat, get

Gordian knot, abecedarian, addle, amaze, answer, answer conclusively, argue down, astonish, astound, bafflement, balk, bamboozle, beat, bewilderment, blast, boggle, bother, brave, bring up short, buffalo, challenge, check, checkmate, circumvent, confound, confoundment, confront, confusion, confute, contradict, contravene, controvert, counter, counteract, countermand, counterwork, cross, crush, crux, dabbler, dash, daze, defeat, defy, demolish, deny, destroy, dilemma, dilettante, discomfit, discomposure, disconcert, disconcertedness, disconcertion, disconcertment, discountenance, dish, dismay, dismiss, dispose of, disrupt, disturbance, dumbfound, elude, embarrassment, enigma, faze, finish, fix, floor, flummox, flurry, fluster, foil, frustrate, fuddle, get, jam, keep in suspense, knock the chocks, knot, knotty point, lick, maze, muddle, mystery, node, nodus, nonprofessional, overcome, overthrow, overturn, overwhelm, oxymoron, paradox, paralyze, parry, perplexity, perturbation, pickle, plight, pons asinorum, poser, pother, predicament, problem, put to silence, puzzlement, quandary, rattle, rebut, reduce to silence, refute, riddle, ruin, sabotage, scotch, scrape, settle, shock, shut up, silence, smash all opposition, smatterer, spike, spoil, squash, squelch, stew, stick, stonewall, stop, stump, stun, stymie, subvert, take aback, teaser, throw, thwart, tyro, unassuredness, undermine, upset, vexed question