extracurricular

课外的、正课以外的

She joined several extracurricular clubs during her first year of college.

她大一时参加了好几个课外社团。

业余的、本职以外的

His extracurricular research has nothing to do with his day job.

他在本职工作以外做的研究跟正职毫无关系。

婚外的、偷情的口语，多带戏谑

Everyone in the office suspected he had some extracurricular interests.

办公室里的人都怀疑他在外面有婚外情。

课外活动美式，口语，常用复数

Colleges look at your grades as well as your extracurriculars.

大学除了看成绩，也会看你的课外活动表现。