one-armed bandit

one-armed bandit idiom
A slot machine, as in It's amazing how many people think they can make money playing a one-armed bandit. This term refers to both appearance and function: the operating lever looks like an arm, and the machine in effect robs players, since it “wins” and keeps the player's money in an overwhelming majority of instances. [c. 1930]

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Comments
Improve this definition.
Do you have more to add? Share your linguistic knowledge or observation.
/Register to save your comments.