underarm
un·de·rarm
adjective
adverb
Origin
From under- + arm. The armpit sense is not old, historically speaking (1920s), and it is believed to have arisen as a euphemism in advertising.
WordNet 2.1 (Princeton University). Wiktionary (CC BY-SA). CMU Pronouncing Dictionary. WordNet 2.1 Copyright Princeton University. All rights reserved. Wiktionary content is available under the Creative Commons Attribution-ShareAlike Licence.