What is the Latin word for diagonal?

The usual Latin words for “diagonal” are diagōnālis, dĭăgōnĭŏs, līnea. The right choice depends on the sense; see the distinctions below.

English → Latin

“diagonal” in Latin

diagōnālisdiagonal dĭăgōnĭŏsadj., diagonal līneaA linen thread.

The English word diagonal itself goes back to Latin diagōnālis.

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

diagonal

diagonalis and (Greek) diagonios; also feminine, diagonia (all Vitr.). A diagonal, diagonalis (or diagonios, or diagonia, or diagonii) linea (all Vitr.).

Quick answer

What is the Latin word for diagonal?: The usual Latin words for “diagonal” are diagōnālis, dĭăgōnĭŏs, līnea. 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.