Rhythm

Etymology

From Greek "rhythmos" (measured flow, recurrence, proportion), from "rhein" (to flow) — the same root as in "rheum." The idea is patterned, recurring motion, first of anything in flux, later fixed on the ordering of sound in time.

noun · /RITH-uhm/
The pattern of sounds and silences in time — how music is organized into beats and stresses.
What it names
The felt pulse and its subdivisions, the thing you tap your foot to, giving a handle to the time dimension of any art that unfolds — music, poetry, even film editing.
Example
The song’s hypnotic rhythm came from a clap that landed just a hair behind each beat.
Related idea
Rhythm is the pattern of durations and accents; tempo is merely how fast that pattern is played. You can keep an identical rhythm and slow the tempo, or speed the tempo and keep the same rhythm.