1. of or relating to a fraternity or society of usually men - a fraternal order • Pertains to noun: brotherhood • Derivationally related forms: fraternity 2. like or characteristic of or befitting a brother - brotherly feelings - close fraternal ties • Syn: brotherly, brotherlike • Ant: sisterly (for: brotherly) • Derivationally related forms: brother (for: brotherly) 3.(of twins) derived from two separate fertilized ova - fraternal twins are biovular • Syn: biovular • Ant: identical