Idiocy

Id"i*o*cy (ĭd"ĭ*?*s?), n. [From idiot; cf. Gr. ? uncouthness, want of education, fr. ?. See Idiot, and cf. Idiotcy.] The condition or quality of being an idiot; absence, or marked deficiency, of sense and intelligence.

I will undertake to convict a man of idiocy, if he can not see the proof that three angles of a triangle are equal to two right angles.