illicit

adjectives

contrary to accepted morality (especially sexual morality) or convention
"an illicit association with his secretary"
illicit
antonym
licit
is similar to
characterized by adultery
"an adulterous relationship"; "extramarital affairs"; "the extracurricular activities of a philandering husband"
adulterous, extracurricular, extramarital
is similar to
not morally right or permissible
"unlawful love"
unlawful
contrary to or forbidden by law
"an illegitimate seizure of power"; "illicit trade"; "an outlaw strike"; "unlawful measures"
illegitimate, illicit, outlaw, outlawed, unlawful
is derived from
illicitness