Source : Webster's Revised Unabridged Dictionary (1913)

Vocalize \Vo"cal*ize\, v. t. [imp. & p. p. {Vocalized}; p. pr. &
   vb. n. {Vocalizing}.] [Cf. F. vocaliser.]
   1. To form into voice; to make vocal or sonant; to give
      intonation or resonance to.

            It is one thing to give an impulse to breath alone,
            another thing to vocalize that breath. --Holder.

   2. To practice singing on the vowel sounds.