Meaning

noun a close friend who accompanies his buddies in their activities

originFirst appears c. 1788, in the writings of Charles Dibdin, of uncertain origin. Possibly from *bruddy, *bruthy, a child-talk alteration of brother. Alternatively, perhaps from British colloquial butty (“companion”), also the form of an older dialect term meaning workmate, associated with coal mining. Itself believed derived from 1530 as booty fellow, a partner with whom one shares booty or loot.…

Etymology from Wiktionary, CC BY-SA 3.0