1. of or befitting a brother or brothers; brotherly.
  2. of or being a society of men associated in brotherly union, as for mutual aid or benefit: a fraternal order; a fraternal association.

Origin of fraternal

1375–1425; late Middle English < Latin frātern(us) fraternal (derivative of frāter brother) + -al1
Related formsfra·ter·nal·ism, nounfra·ter·nal·ly, adverbin·ter·fra·ter·nal, adjectivein·ter·fra·ter·nal·ly, adverbnon·fra·ter·nal, adjectivenon·fra·ter·nal·ly, adverbpre·fra·ter·nal, adjectivepre·fra·ter·nal·ly, adverbqua·si-fra·ter·nal, adjectivequa·si-fra·ter·nal·ly, adverbun·fra·ter·nal, adjectiveun·fra·ter·nal·ly, adverb Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for interfraternal


  1. of or suitable to a brother; brotherly
  2. of or relating to a fraternity
  3. designating either or both of a pair of twins of the same or opposite sex that developed from two separate fertilized ovaCompare identical (def. 3)
Derived Formsfraternalism, nounfraternally, adverb

Word Origin for fraternal

C15: from Latin frāternus, from frāter brother
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for interfraternal



early 15c., from Middle French fraternel and directly from Medieval Latin fraternalis, from Latin fraternus "brotherly" (see fraternity). The noun meaning "fraternal twin" is recorded by 1911.

Online Etymology Dictionary, © 2010 Douglas Harper

interfraternal in Medicine


  1. Of or relating to brothers.
  2. Of, relating to, or being a twin developed from two separately fertilized ova; dizygotic.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.