St Valentine's Day

Từ điển Oxford Advanced Learner 8th

St ˈValentine's Day 7 [St Valentine's Day] BrE [ˌsnt ˈvæləntaɪnz deɪ] NAmE [ˌseɪnt ˈvæləntaɪnz deɪ] noun
the day (14 February), when people send a card to the person that they love, often without signing their name on it

Culture:
The cards are called Valentine cards or Valentines. They usually have designs of hearts, etc. on them and often include a sentimental or funny message. People sending Valentine cards do not usually sign their name. Sometimes people have a similar short message printed in a newspaper or magazine, and may also give each other gifts such as flowers or chocolates. The people who send or receive gifts, etc. in this way are also known as Valentines.