Emily Dickinson Lexicon

RHYTHM, or RHYTH'MUS, n. [Gr. ῥυθμος.]

1. In music, variety in the movement as to quickness or slowness, or length and shortness of the notes; or rather the proportion which the parts of the motion have to each other. – Encyc.
2. Meter; verse; number. – Howell.
3. Rhythm is a successive motion subject to certain properties. In poetry, it is the relative duration of the moments employed in pronouncing the syllables of a verse; and in music, the relative duration of the sounds that enter into the composition of an air. – Anarch. Translation.