Origin of underarm
Examples from the Web for underarm
Finishing—Sew up seams at underarm and sleeve seams, insert sleeves into arm holes, having seams meet at underarm.Juvenile Styles, Volume 4|Mary Hoyer
Shape the jacket by crocheting the sleeves and underarm seams together.The Library of Work and Play: Needlecraft|Effie Archer Archer
Continue knitting in extra or lesser length to underarm, for armhole and for sleeves.Beehive for Bairns, Vol. 2|Various
In fitting the outside the back is pinned on to the lining firmly, then the front and finally at the underarm seams.Textiles and Clothing|Kate Heintz Watson
An underarm dart gives a smooth adjustment over each hip, and in these darts are inserted the back edges of the vest.
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.