Adjectives

(s)extracurricularoutside the regular academic curriculum“sports and drama are popular extracurricular activities”
(s)extracurricularoutside the regular duties of your job or profession
(s)adulterous, extramarital, extracurricularcharacterized by adultery“an adulterous relationship”, “extramarital affairs”, “the extracurricular activities of a philandering husband”