discovered check

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun chess A situation in a game of chess where the opponent's king is put in check, not by the piece that was just moved but by one whose line of sight to the king was opened by the move.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a check on the opponent's king that is delivered by moving a piece out of the line of attack by a queen or rook or bishop