show one's true colors


Reveal oneself as one really is, as in We always thought he was completely honest, but he showed his true colors when he tried to use a stolen credit card. This expression alludes to the antonym, false colors, that is, sailing under a flag other than one's own. [Late 1700s]

QUIZZES

Can You Ace This Quiz About “Compliment” vs. “Complement”?
Take this quiz to see if you really know the difference between “compliment” and “complement"!
Question 1 of 11
“Compliment” and “complement” had a shared meaning a long time ago, but today they are no longer interchangeable.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.