also: にちげつ
Refers to the celestial bodies themselves, often in poetic or literary contexts.
The sun and moon are shining in the sky.
Metaphorical extension: the passing of time, as marked by the sun and moon. Often used in set phrases like 日月が経つ.
How quickly the days and months pass.
short period of time; brief span
long period of time; many years
leisure; peaceful quiet; free time
the sun, moon, and stars; heavenly bodies
Standard kanji form; reading じつげつ is the most common and unmarked.
Alternate reading; used especially for sense 3 (Sunday and Monday) and sometimes for the passage of time.
Compound of 日 (sun, day) and 月 (moon, month). The reading じつげつ uses the on'yomi, while にちげつ mixes on'yomi and kun'yomi. The time-related sense is a natural extension of the celestial bodies marking the passage of time.