1. very auspicious day for all types of occasions (one of the six special days in the Japanese lunisolar calendar)Yojijukugo (four character compound)
For the wedding date, you want to choose an auspicious day such as “taian” (a lucky day in the recurring six-day calendar when it is best to do important things such as weddings and trips) or “tomobiki” (a day in the same calendar when one’s luck is said to affect other people and therefore a good day for weddings but a bad day for funerals).— Jreibun