Source : Webster's Revised Unabridged Dictionary (1913)

Rhythmic \Rhyth"mic\ (-m[i^]k), Rhythmical \Rhyth"mic*al\
   (-m[i^]*kal), a. [Gr. ????: cf. L. rhythmicus, F.
   rhythmique.]
   Pertaining to, or of the nature of, rhythm

         Day and night I worked my rhythmic thought. --Mrs.
                                                  Browning.

   {Rhythmical accent}. (Mus.) See {Accent}, n., 6
   (c) .

Source : WordNet®

rhythmical
     adj : recurring with measured regularity; "the rhythmic chiming of
           church bells"- John Galsworthy; "rhythmical prose"
           [syn: {rhythmic}] [ant: {unrhythmical}]