Source : Webster's Revised Unabridged Dictionary (1913)

Postpositive \Post*pos"i*tive\, a. [See {Postpone}.]
   Placed after another word; as, a postpositive conjunction; a
   postpositive letter. -- {Post*pos"i*tive*ly}, adv.

Source : WordNet®

postpositive
     adj : (of a modifier) placed after another word