noun
   1. a strong, regular repeated pattern of movement or sound.
  2. the systematic arrangement of musical sounds, according to duration and periodical stress.
   3. a particular pattern formed by such arrangement: a slow waltz rhythm.
  4. the measured flow of words and phrases in verse or prose as determined by the length of and stress on syllables.
   5. a regularly recurring sequence of events or actions.

          — DERIVATIVES rhythmless adjective.

          — ORIGIN French rhythme, from Greek rhuthmos, related to rhein ‘to flow’.
in Concise Oxford English Dictionary