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  1. of, situated, or for use under the arm or in the armpit: an underarm deodorant.
  2. underhand: an underarm pitch in softball.
  1. armpit.
  1. underhand.

Origin of underarm

First recorded in 1810–20; under- + arm1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for underarm

Historical Examples

  • Sew up the sleeves and underarm seams and turn back the cuffs.

    Handbook of Wool Knitting and Crochet


  • Baste seams of sleeve and underarm all in one long seam on right side.

  • Mark with tracing or pencil the new seam for underarm if you must change it.

  • Baste, with the seams on the outside, shoulder, and underarm seams.

  • Work even to underarm 29 inches or desired length to underarm.

British Dictionary definitions for underarm


  1. (of a measurement) extending along the arm from wrist to armpit
  2. sport of or denoting a style of throwing, bowling, or serving in which the hand is swung below shoulder level
  3. below the arm
  1. in an underarm style
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 underarm


1816, "underhand" (in reference to a style of throwing), from under + arm (n.1). First attested 1908 in dressmaking sense of "seams on the lower half of the arm-hole;" as a euphemism for armpit, it is attested from 1930s, popularized by advertisers.

Online Etymology Dictionary, © 2010 Douglas Harper

underarm in Medicine


  1. Located, placed, or used under the arm.
  1. The armpit.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.