Meaning

adjective of or relating to a fraternity or society of usually men

adjective (of twins) derived from two separate fertilized ova

adjective like or characteristic of or befitting a brother

originPIE word *bʰréh₂tēr Borrowed from Middle French fraternel, from Medieval Latin frāternālis (“fraternal”), from Latin frāternus (“of or pertaining to a brother, fraternal”), from frāter (“brother”).

Etymology from Wiktionary, CC BY-SA 3.0