not allowed by the law 非法的；違法的 illicit drugs 違禁藥物
not approved of by the normal rules of society 違背社會常規的；不正當的 an illicit love affair 不正當的風流韻事
Word Originearly 16th cent.: from French, or from Latin illicitus, from in- ‘not’ + licitus ‘allowed’, from the verb licere.