The story
From Russian "boy", combat, battle; hence, Yiddish "boyuvke", combat unit, commando. e.g. The last decade of the 19th century in Babruysk was characterized by pogroms as a result of the assassination of the Russian emperor Alexander II. However, most of the attacks were repelled by self-organized Jewish armed units called boyuvkes.
Etymology from Wiktionary, CC BY-SA 4.0.