a serious or impassive facial expression that conceals one's true feelings about something, especially a desire to laugh.
Origin of straight face
First recorded in 1890–95
Related formsstraight-faced, adjectivestraight-fac·ed·ly [streyt-fey-sid-lee, -feyst-lee] /ˈstreɪtˈfeɪ sɪd li, -ˈfeɪst li/, adverb
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for straight face
a serious facial expression, esp one that conceals the impulse to laugh
Derived Formsstraight-faced, adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Idioms and Phrases with straight face
see keep a straight face.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.