secret Santanoun
uk/ˌsiː.krət ˈsæn.tə//ˌsiː.krət ˈsæn.t̬ə/[ U ] an arrangement in which each person in a group buys a Christmas present for one other person, without the person knowing who bought the present:
Do you want to be in the office secret Santa?
I need to buy a secret Santa gift.
[ C ] a person who buys a present in this arrangement:
I wonder who my secret Santa was!