extracurricular
adjective uk/ˌek.strə.kəˈrɪk.jə.lər/ us/ˌek.strə.kəˈrɪk.jə.lɚ/
（活动、主题等）课外的
An extracurricular activity or subject is not part of the usual school or college course.
humorous业余的，分外的；（尤指性关系）婚外的
used to refer to something a person does secretly or unofficially and not within their normal work or relationship, especially a sexual relationship
He detailed the future president's extracurricular activities while governor. 他把未来总统当州长时的风流韵事一五一十全说了出来。