Source : Webster's Revised Unabridged Dictionary (1913)

Alliterative \Al*lit"er*a*tive\ (?; 277), a.
   Pertaining to, or characterized by, alliteration; as,
   alliterative poetry. -- {Al*lit"er*a*tive*ly}, adv. --
   {Al*lit"er*a*tive*ness}, n.

Source : WordNet®

alliterative
     adj : having the same consonant at the beginning of each stressed
           syllable; "alliterative verse"