The word rook has two unrelated meanings:

1. A large black bird in the crow family, common in Europe and parts of Asia. Rooks are intelligent, social birds that live in large groups called rookeries, often building their nests together in tall trees. They're known for their loud cawing and clever problem-solving abilities. Like their crow cousins, rooks can use tools and remember human faces.
2. A powerful chess piece that looks like a castle tower and moves in straight lines across the board, either horizontally or vertically, as many squares as are open. The rook is one of the most valuable pieces in chess after the queen. In the opening moves of a chess game, players often castle, a special move that brings the rook closer to the center while moving the king safely to the side.