bare skin; nakedness:
They were sunbathing in their birthday suits.
a state of total nakedness, as at birth
Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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birthday suit definition
To be “in one's birthday suit” is to be completely naked (as people are at birth).
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.