Verb

• S: (v) perplex, vex, stick, get, puzzle, mystify, baffle, beat, pose, bewilder, flummox, stupefy, nonplus, gravel, amaze, dumbfound (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"
• S: (v) thwart, queer, spoil, scotch, foil, cross, frustrate, baffle, bilk (hinder or prevent (the efforts, plans, or desires) of) "What ultimately frustrated every challenger was Ruth's amazing September surge"; "foil your opponent"
• S: (v) baffle, regulate (restrain the emission of (sound, fluid, etc.))

Adjective

• S: (adj) baffling, elusive, knotty, problematic, problematical, tough (making great mental demands; hard to comprehend or solve or believe) "a baffling problem"; "I faced the knotty problem of what to have for breakfast"; "a problematic situation at home"