English → Latin
“illegal” in Latin
contrāriusopposite, opposed, contrary, conflicting, witherwardprohibeōto hold back or before, keep or ward off, restrain; avert; prevent, hinder; to forbid, prohibit; to keep, preserve, defe
The English word illegal itself goes back to Latin lēx, through illegalis.
Riddle & Arnold A Copious and Critical English–Latin Lexicon, 1864
illegal
non legitimus (☞ avoid illegitimus): legi repugnans or contrarius: legibus vetitus († Hor.): quod lex vetat or prohibet. It is illegal to condemn a Roman citizen to death except in the Comitia Curiata, lex de capite civis Romani nisi Comitiis Centuriatis statui vetat. It is illegal to elect two magistrates of the same family, leges duo ex una familia magistratus creari vetant or prohibent (Caes.).
Quick answer
- What is the Latin word for illegal?
- The usual Latin words for “illegal” are contrārius, prohibeō. 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.