fill with apprehension or alarm; cause to be unpleasantly surprised; "I was horrified at the thought of being late for my interview"; "The news of the executions horrified us"
a chess move constituting an inescapable and indefensible attack on the opponent's king
complete victory
place an opponent's king under an attack from which it cannot escape and thus ending the game; "Kasparov checkmated his opponent after only a few moves"
a crosspiece spreading the gunnels of a boat; used as a seat in a rowboat
hinder or prevent (the efforts, plans, or desires) of; "What ultimately frustrated every challenger was Ruth's amazing September surge"; "foil your opponent"
throw into great confusion or disorder; "Fundamental Islamicists threaten to perturb the social order in Algeria and Egypt"
disturb in mind or make uneasy or cause to be worried or alarmed; "She was rather perturbed by the news that her father was seriously ill"
cause a celestial body to deviate from a theoretically regular orbital motion, especially as a result of interposed or extraordinary gravitational pull; "The orbits of these stars were perturbed by the passings of a comet"
disturb or interfere with the usual path of an electron or atom; "The electrons were perturbed by the passing ion"