day of the Hare
Archaic term from the traditional Chinese zodiac calendar; refers to the day associated with the Hare (卯) in the sexagenary cycle. Rarely used in modern Japanese outside historical or cultural contexts.
In the old calendar, the day of the Hare was associated with specific events.
卯 (う, 'Hare', the fourth sign of the Chinese zodiac) + の (possessive particle) + 日 (ひ, 'day'). The term follows the pattern of naming days after the twelve zodiac signs in the traditional sexagenary cycle.