Webster's Revised Unabridged Dictionary · 1913

Idiotic

Idiotic , adjective

[Latin idioticus ignorant, Greek {not transcribed}: compare French idiotique. See Idiot.]

1.
Common; simple. [Obsolete] — Blackwall
2.
Pertaining to, or like, an idiot; characterized by idiocy; foolish; fatuous; as, an idiotic person, speech, laugh, or action.

Also: Idiotical