noun
first day of the fourth month in the lunisolar calendar
Rare historical term referring to a specific date in the old Japanese calendar, around early May in the modern calendar. The name literally means 'cotton-removing first day', associated with the custom of changing from padded winter clothing to lighter garments.
旧暦では、綿抜の朔日は衣替えの目安とされていた。
In the old calendar, the first day of the fourth month was considered a marker for the seasonal change of clothing.
Refers to the modern seasonal clothing change (June 1 and October 1), while 綿抜の朔日 is a historical date for the same custom in the lunisolar calendar.
The term combines 綿 (cotton), 抜く (to remove), and 朔日 (first day of the month), referring to the day when padded winter garments were put away. The exact historical origin is uncertain, but it is tied to Heian-era court customs.