Source : Webster's Revised Unabridged Dictionary (1913)

Avuncular \A*vun"cu*lar\, a. [L. avunculus uncle.]
   Of or pertaining to an uncle.

         In these rare instances, the law of pedigree, whether
         direct or avuncular, gives way.          --I. Taylor.

Source : WordNet®

avuncular
     adj 1: being or relating to an uncle
     2: like an uncle in kindness or indulgence; "showed avuncular
        concern"