Definitions for "Discovered attack"
Keywords:  rook, uncovers, bishop, pawn, unmasks
A move which opens up an attack from a bishop, rook or queen. After the moves 1. e2-e4 e7-e5 2. Qd1-g4?, a move by the Black d-pawn would be a DISCOVERED ATTACK on the White Queen. Also called an AMBUSH.
a move which unmasks an attack by another piece
an attack where a piece moves and uncovers a line for another piece which does the attacking