I. ˈsīd-ˌärm noun
Date: 1689
: a weapon (as a sword, revolver, or bayonet) worn at the side or in the belt
II. adjective
Date: 1908
: of, relating to, using, or being a throw (as in baseball) in which the arm is not raised above the shoulder and the ball is thrown with a sideways sweep of the arm between shoulder and hip
sidearm delivery
a sidearm pass
• sidearm adverb