What is the Latin word for unallowable?

The usual Latin words for “unallowable” are inconcessus, impermissus, vetō. The right choice depends on the sense; see the distinctions below.

English → Latin

“unallowable” in Latin

inconcessusnot allowed, forbidden, impossible impermissusunlawful vetōto forbid, prevent, prohibit; to advise not to; to oppose, veto

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

unallowable

quod admitti non potest: quod non licet: inconcessus (post-Augustan and very rare; Verg., Quint.): impermissus († Hor.): vetitus (forbidden).

Quick answer

What is the Latin word for unallowable?: The usual Latin words for “unallowable” are inconcessus, impermissus, vetō. 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.