Il‐lic″it (?), a. [L. illicitus; pref. il- not + licitus, p. p. of licere to be allowed or permitted: cf. F. illicite. See In- not, and License.] Not permitted or allowed; prohibited; unlawful; as, illicit trade; illicit intercourse; illicit pleasure.
One illicit... transaction always leads to another. Burke.
— Il‐lic″it‐ly, adv. — Il‐lic″it‐ness, n.