What is the Latin word for infectious?

The usual Latin words for “infectious” are contāgiōsus, pestilentia. The right choice depends on the sense; see the distinctions below.

English → Latin

“infectious” in Latin

contāgiōsuscontagious, infectious pestilentiainfectious or contagious disease; plague, pestilence

The English word infectious itself goes back to Latin īnfectiōsus.

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

infectious

contagiosus (late, but necessary as technical term). An infectious disorder, contagio morbi: pestilentia (pestilence; pestilential epidemic).

Quick answer

What is the Latin word for infectious?: The usual Latin words for “infectious” are contāgiōsus, pestilentia. 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.