It is doubtful that an insaner plan of campaign than this was ever devised by any man in command of a great army.
I mean him no discourtesy, and I am not charging—nor even imagining—that he is insaner than the rest of the human race.
An instant later there was a mad tugging at the front door bell, and an insaner clatter at the knocker.
1550s, from Latin insanus "mad, insane; outrageous, excessive, extravagant," from in- "not" (see in- (1)) + sanus "well, healthy, sane" (see sane). Originally only of persons; of actions, from 1842. Cf. lunatic; and Italian pazzo "insane," originally a euphemism, from Latin patiens "suffering." German verrückt, literally past participle of verrücken "to displace," "applied to the brain as to a clock that is 'out of order' " [Buck]. The noun meaning "insane person" is attested from 1786.
insane in·sane (ĭn-sān')
Of, exhibiting, or afflicted with insanity.