Synonyms of nonplussed

Verb

1. perplex, vex, stick, get, puzzle, mystify, baffle, beat, pose, bewilder, flummox, stupefy, nonplus, gravel, amaze, dumbfound, confuse, throw, fox, befuddle, fuddle, bedevil, confound, discombobulate

usage: 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"

Adjective

1. at a loss(predicate), nonplused, nonplussed, puzzled, perplexed (vs. unperplexed)

usage: filled with bewilderment; "at a loss to understand those remarks"; "puzzled that she left without saying goodbye"