The Collaborative International Dictionary of English v.0.48:

Intone \In*tone"\, v. t. [imp. & p. p. Intoned; p. pr. & vb.
   n. Intoning.] [LL. intonare, intonatum; pref. in- in + L.
   tonus tone. See Tone and cf. Entune, Intonate.]
   1. To utter with a musical or prolonged note or tone; to
      chant; as, to intone the church service.
      [1913 Webster]

   2. To speak with a distinctive or unusual tone in the voice,
      or in a monotone; as, the professor intoned his lectures
      as though by rote.
      [PJC]