adjective (a)

• of or relating to a fraternity or society of usually men(adj.pert)

  Example:
  A fraternal order.
  

  source: wordnet30
• (of twins) derived from two separate fertilized ova(adj.all)

  Example:
  Fraternal twins are biovular.
  

  Synonym:
  biovular
  Antonym:
  identical, monovular
  

  source: wordnet30
• like or characteristic of or befitting a brother(adj.all)

  Example:
  Close fraternal ties.
  

  Synonym:
  brotherlike, brotherly
  Antonym:
  sisterlike, sisterly, sororal
  

  source: wordnet30
• Of, pertaining to, or involving, brethren; becoming to brothers; brotherly; as, fraternal affection; a fraternal embrace.(adjective)

  source: webster1913