What is "raglan sleeve"

raglan sleeve \rag"lan sleeve`\ (r[a^]g"lan sl[=e]v`), n. A sleeve joined to the body of a garment by a long slanting seam starting at the neck and continuing around the armhole. Contrasted to a set-in sleeve.

n. a sleeve that extends in one piece to the neckline of a coat or sweater with seams from the armhole to the neck

A raglan sleeve is a type of sleeve whose distinguishing characteristic is to extend in one piece fully to the collar, leaving a diagonal seam from underarm to collarbone giving the garment a relatively undefined look.

It is named after Lord Raglan, the 1st Baron Raglan, who is said to have worn a coat with this style of sleeve after the loss of his arm in the Battle of Waterloo. The Raglan sleeve was invented by coat producer Aquascutum for Lord Raglan to allow him room to use his sword in battle. It gave greater movement to the wearer, instead of the usual sleeve head which was prefixed.

The raglan mid-length sleeve is a popular undergarment (worn under the jersey) for baseball teams in the United States.