What is the Latin word for unlawful?

The usual Latin words for “unlawful” are inconcessus, vetō, nefās; also inīquus. The right choice depends on the sense; see the distinctions below.

English → Latin

“unlawful” in Latin

inconcessusnot allowed, forbidden, impossible vetōto forbid, prevent, prohibit; to advise not to; to oppose, veto nefāswrong; (moral) offense; wicked act; misdeed or misdoing; forbidden deed or act inīquusunjust, unfair; unequal, uneven; unfavourable, disadvantageous

Riddle & Arnold A Copious and Critical English–Latin Lexicon, 1864

unlawful

inconcessus (poetical and Quint.): non concessus: vetitus: nefas (against the laws of God and man): non legitimus (☞ illegitimus to be avoided): iniquus: non justus. Unlawful means, artes malae: to be unlawful, non licere; illicitum esse. [On illicitus, Vid: ILLICIT.]

Quick answer

What is the Latin word for unlawful?: The usual Latin words for “unlawful” are inconcessus, vetō, nefās; also inīquus. The right choice depends on the sense; see the distinctions below.

Entry from J. E. Riddle & T. K. Arnold, A Copious and Critical English–Latin Lexicon (rev. C. Anthon, New York: Harper, 1864), digitised by Fergus J. P. Walsh, CC BY-SA 4.0; Latin markup adapted by latindictionary.co.