noun, noun which may take the genitive case particle 'no'
leap; intercalary; embolism
Refers to the insertion of an extra day, month, or similar unit into a calendar to keep it aligned with astronomical events. Most commonly seen in compounds like うるう年 (leap year) and うるう秒 (leap second).
This year is a leap year, so February has 29 days.
Leap seconds are inserted because the Earth's rotation is irregular.
leap day
intercalary month; leap month
leap second
The origin is uncertain; the word is native Japanese and the kanji 閏 is a semantic borrowing from Chinese.