one-armed bandit
noun🔊/ˌwʌn ɑːmd ˈbændɪt/
🔊/ˌwʌn ɑːrmd ˈbændɪt/
(North American English, British English) (also slot machine especially in North American English)
a gambling machine that you put coins into and that gives money back if particular pictures appear together on the screen; a similar game, played online