a basin for washing the hands (`wash-hand basin' is a British expression)
a bathroom sink that is permanently installed and connected to a water supply and drainpipe; where you can wash your hands and face; "he ran some water in the basin and splashed it on his face"
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"