What is "idiotism"

Idiotism \Id"i*ot*ism\, n. [F. idiotisme, L. idiotismus the way of fashion of a private person, the common or vulgar manner of speaking, Gr. ?, fr. ? to put into or use common language, fr. ?. See Idiot.]

1. An idiom; a form, mode of expression, or signification, peculiar to a language.

   Scholars sometimes give terminations and idiotisms, suitable to their native language, unto words newly invented.
   --M. Hale.

2. Lack of knowledge or mental capacity; idiocy; foolishness.

   Worse than mere ignorance or idiotism.
   --Shaftesbury.

   The running that adventure is the greatist idiotism.
   --Hammond.

Etymology 1 n. (context dated English) Very severe mental retardation. Etymology 2

n. 1 idiom. 2 An overly literal translation of an idiom.