Source : Webster's Revised Unabridged Dictionary (1913)

Vowelize \Vow"el*ize\, v. t.
   To give the quality, sound, or office of a vowel to.

Source : WordNet®

vowelize
     v : pronounce as a vowel; "between two consonants, this liquid
         is vowelized" [syn: {vocalize}, {vocalise}, {vowelise}]