The Collaborative International Dictionary of English v.0.48:

Intonate \In"to*nate\, v. i. [imp. & p. p. Intonated; p. pr. &
   vb. n. Intonating.] [See Intone.]
   [1913 Webster]
   1. (Mus.) To sound the tones of the musical scale; to
      practice the sol-fa.
      [1913 Webster]

   2. To modulate the voice in a musical, sonorous, and measured
      manner, as in reading the liturgy; to intone.
      [1913 Webster]