1. a small elevation of the skin containing pus
2. any small elevation like a blister or pimple
Webster’s New World College Dictionary, Fourth Edition, compiled by the
editors of Webster’s New World Dictionaries. Copyright © 2010 by Houghton
Mifflin Harcourt. Published by Houghton Mifflin Harcourt. All rights reserved.
Word origin of 'pustule'L pustula, blister, pimple < IE base *pu-, echoic of blowing out cheeks, puffing > Gr physa, breath, bubble