the.com/fraternity

means A group of men formally bonded by shared membership, rituals, or purpose — often an organization, especially a college social club.

from From Latin 'frater' meaning brother, through 'fraternitas' (brotherhood). It entered English via Old French 'fraternite' in the medieval period, originally describing religious brotherhoods and guilds before narrowing, much later, to the Greek-lettered campus houses the word now conjures.