noun
very auspicious day
Refers to a day considered exceptionally lucky in the traditional Japanese calendar, often used in contexts like weddings or important ceremonies.
結婚式は大明日に行うことにした。
We decided to hold the wedding on a very auspicious day.
大安 is a specific day in the six-day cycle (rokuyo) considered auspicious, while 大明日 is a broader term for any exceptionally lucky day, not tied to that cycle.
Compound of 大 (great) + 明日 (tomorrow, but here likely used in the sense of 'bright day' or 'auspicious day'). The exact historical derivation is uncertain; the term is used in traditional calendar contexts.