cheat on

cheat on idiom
Be sexually unfaithful to, as in They broke up right after she found he was cheating on her. [Colloquial; 1920s]

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.