domino
n. countablen. a small, flat, rectangular block used in a game. Each piece has two halves, usually marked with a certain number of dots.
n. a small rectangular tile used in gaming, typically divided into two square faces each marked with a number of pips or left blank.
He placed the last domino on the table to win the game.
The children spent the afternoon lining up every domino in the box to create a long chain they could knock over.
The collapse of the regional bank triggered a domino effect, causing investors to withdraw capital from similar institutions and threatening the stability of the entire financial sector.
Commonly used in the compound noun 'domino effect' to describe a cumulative effect produced when one event sets off a chain of similar events.