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: Webster's Revised Unabridged Dictionary (1913)