1.
same day; that very day
On the same day as another event or action; immediately without delay.
即日 emphasizes that something happens on the very same day as another event, with no waiting period. Often used as a noun modifier before another noun.
Common collocations
- 即日配達: same-day delivery
- 即日発送: same-day shipping
- 即日回答: same-day response
- 即日開票: same-day vote counting
- 即日完売: sold out on the same day
Similar words
- 当日: on that day, the day in question (neutral — does not emphasize speed)
- 本日: today (formal, used in announcements)
- 即日 specifically highlights the speed or immediacy, implying no delay
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Formal. Common in business, advertising, and official announcements. In casual speech, その日のうちに (within that day) is more natural.