The Collaborative International Dictionary of English v.0.48:

Fraternal \Fra*ter"nal\, a.[F. fraternel, LL. fraternalis, fr.
   L. fraternus, fr. frater brother. See Brother.]
   Of, pertaining to, or involving, brethren; becoming to
   brothers; brotherly; as, fraternal affection; a fraternal
   embrace. -- Fra*ter"nal*ly, adv.
   [1913 Webster]

         An abhorred, a cursed, a fraternal war.  --Milton.
   [1913 Webster]

         Fraternal love and friendship.           --Addison.
   [1913 Webster]

WordNet (r) 3.0 (2006):

fraternal
    adj 1: of or relating to a fraternity or society of usually men;
           "a fraternal order"
    2: (of twins) derived from two separate fertilized ova;
       "fraternal twins are biovular" [syn: fraternal, biovular]
       [ant: identical, monovular]
    3: like or characteristic of or befitting a brother; "brotherly
       feelings"; "close fraternal ties" [syn: brotherly,
       brotherlike, fraternal] [ant: sisterlike, sisterly,
       sororal]

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "fraternal":
   Christian, Christlike, Christly, affectionate, agreeable, amiable,
   amicable, benign, benignant, brotherly, compassionate, congenial,
   decent, favorable, friendlike, friendly, good, gracious,
   harmonious, human, humane, idealistic, intellectual, kind,
   kindhearted, kindly, kindly-disposed, loving, neighborlike,
   neighborly, nice, peaceable, pleasant, simpatico, sisterly,
   sociable, softhearted, sympathetic, sympathique, sympathizing,
   tender, tenderhearted, unhostile, warm, warmhearted, well-affected,
   well-disposed, well-intentioned, well-meaning, well-meant