1.
the 15th of the month; fifteen days
Either the 15th day of a calendar month or a duration of fifteen days. Context determines which meaning applies.
Follows the standard pattern for dates: number + 日 (or special readings for 1st–10th, 14th, 20th, 24th).
Usage
- For 'the 15th day of the month': used alone or with the month name (五月十五日).
- For 'fifteen days' (duration): typically add 間 → 十五日間.
Cultural note: The 15th of the month historically marked the full moon in the lunar calendar; 十五夜 (lit. 'night of the 15th') refers to the harvest moon festival.