Open English Wordnet
Verbs
(v)perplex, vex, stick, get, puzzle, mystify, baffle, beat, pose, bewilder, flummox, stupefy, nonplus, gravel, amaze, dumbfoundbe a mystery or bewildering to“This beats me!”,
“Got me — I don't know the answer!”,
“a vexing problem”,
“This question really stuck me”