consenting adult
noun [ C ] formal uk/kənˌsen.tɪŋ ˈæd.ʌlt/ us/kənˌsen.tɪŋ ˈæd.ʌlt/
（能决定自己性行为的）已达法定性成熟年龄的成年人
a person who is considered old enough, and therefore responsible enough, to decide if they want sex and who they want to have sex with