Noun | 1. | slot machine - a machine that is operated by the insertion of a coin in a slot coin box - the part of a slot machine that serves as a receptacle for the coins coin slot - a slot through which coins can be inserted into a slot machine machine - any mechanical or electrical device that transmits or modifies energy to perform or assist in the performance of human tasks one-armed bandit, slot - a slot machine that is used for gambling; 'they spend hours and hours just playing the slots' vending machine - a slot machine for selling goods |