The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

WordNet (r) 3.0 (2006):

alliterative
    adj 1: having the same consonant at the beginning of each
           stressed syllable; "alliterative verse"

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "alliterative":
   alliteral, alliterating, assonant, assonantal, belabored, chanting,
   chiming, cliche-ridden, dingdong, harping, humdrum, jingle-jangle,
   jingling, jog-trot, labored, monotone, monotonous, punning, rhymed,
   rhyming, singsong, tedious