rat on


Betray a comrade by giving information, as in He ratted on his best friend to the police. [Slang; early 1900s]

Words Nearby rat on

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.