The Collaborative International Dictionary of English v.0.48:

Akin \A*kin"\, a. [Pref. a- (for of) + kin.]
   1. Of the same kin; related by blood; -- used of persons; as,
      the two families are near akin.
      [1913 Webster]

   2. Allied by nature; partaking of the same properties; of the
      same kind. "A joy akin to rapture." --Cowper.
      [1913 Webster]

            The literary character of the work is akin to its
            moral character.                      --Jeffrey.
      [1913 Webster]

   Note: This adjective is used only after the noun.
         [1913 Webster]

WordNet (r) 3.0 (2006):

akin
    adj 1: similar in quality or character; "a feeling akin to
           terror"; "kindred souls"; "the amateur is closely related
           to the collector" [syn: akin(p), kindred]
    2: related by blood [syn: akin(p), blood-related, cognate,
       consanguine, consanguineous, consanguineal, kin(p)]

Moby Thesaurus II by Grady Ward, 1.0:

80 Moby Thesaurus words for "akin":
   accordant, according, affiliated, affinal, affinitive, agnate,
   agreeable, agreeing, alike, allied, amicable, analogous, at one,
   attuned, avuncular, closely related, cognate, collateral,
   comparable, compatible, concordant, conforming, congeneric,
   congenerous, congenial, connate, connatural, connected,
   consanguine, consanguinean, consanguineous, consonant, conspecific,
   correlative, corresponding, distantly related, empathetic,
   empathic, en rapport, enate, foster, frictionless,
   genetically related, german, germane, harmonious, harmonizing,
   in accord, in concert, in rapport, in tune, incident, inharmony,
   kindred, like, like-minded, matrilateral, matrilineal,
   matroclinous, novercal, of common source, of one mind,
   of the blood, parallel, patrilateral, patrilineal, patroclinous,
   peaceful, related, related by blood, sib, sibling, similar,
   sympathetic, together, understanding, undifferentiated, uniform,
   united, uterine