1.
melody; rhythm; musicality
The melodic or rhythmic quality of music, speech, or poetry.
2.
musical temperament; tuning system
A technical term in music theory referring to the system of dividing the octave into intervals (e.g., equal temperament, just intonation).
Forms
音 (sound) + 律 (rule, rhythm).
Usage
Sense 1 is used broadly for the musical or rhythmic quality of any sound, including poetry and speech. Sense 2 is a technical music theory term referring to specific tuning systems like 平均律 (equal temperament) or 純正律 (just intonation).