Ladies' Day

Từ điển Oxford Advanced Learner 8th

Ladies’ Day [Ladies Day] BrE NAmE
1. 1 (in Britain) the second day of horse racing at ↑Ascot, when women traditionally wear elegant hats and fashionable clothes.
2. 2 (in the US) a special day at a sports or other event when women are admitted free or for less than the normal price.