- women's or children's underwear.
Origin of undies
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- informal women's underwear
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
Word Origin and History for undy
1906, diminutive euphemistic abbreviation for women's underwear (or undergarments).
Online Etymology Dictionary, © 2010 Douglas Harper