adjective
rhythmic
RITH-mik/ˈrɪðmɪk/
Having a regular pattern of beats, movement, or sound.
The drummer's rhythmic tapping follows a steady beat beside the metronome.

Etymology
Rhythmos and the adjective ending give the idea of being related to measured movement. The meaning narrowed from pertaining to rhythm to being marked by regularly recurring beats or accents.
In context
The Earth's motion is constant, steady, and rhythmic. Day and night repeat in a perfect cycle.
More examples
- The dancers match their steps to the rhythmic beat.
- She rows with smooth, rhythmic movements.
- His breathing becomes slow and rhythmic as he falls asleep.
Forms
rhythmic
rhythm noun — A regular pattern of beats or movements.
rhythmically adverb — In a regular pattern of beats.