sidearm /ˈsaɪdˌɑɹm/adverb 1noun 1verb 1forms 5 adverb1 •With one's arm roughly parallel to the ground. noun1 •A personal weapon, either a firearm (handgun type) or a cold weapon (such as a sword), carried on the hip in a belt, sheath, holster, etc., for rapid access. verb1 •To throw a ball with one's arm roughly parallel to the ground.His interest, aside from slinging sinkers as a sidearming right-hander, was medicine. — 2009 formssidearmed · sidearming · sidearms · more sidearm · most sidearm