The Collaborative International Dictionary of English v.0.48:

Monodic \Mo*nod"ic\, Monodical \Mo*nod"ic*al\, a. [Gr. ?.]
   1. Belonging to a monody.
      [1913 Webster]

   2. (Mus.)
      (a) For one voice; monophonic.
      (b) Homophonic; -- applied to music in which the melody is
          confined to one part, instead of being shared by all
          the parts as in the style called polyphonic.
          [1913 Webster]

WordNet (r) 3.0 (2006):

monodical
    adj 1: having a single vocal part [syn: monodic, monodical]