当日 dāngrì on that day
How to remember 当日: 当 act as + 日 sun = on that day.
Characters
How it is used
- That very day / same day - 当日有效 (dāngrì yǒuxiào) valid for the day of issue; 当日往返 (dāngrì wǎngfǎn) a same-day round trip.
- Formal/written; refers to the specific day something happens. Note the reading dāngrì here.
- When 当 means 'in those days/back then' it reads dàng in some uses, but 当日 as 'that day' is dāngrì.