batty · adjective1
From bat + -y. In sense “insane”, attested 1903, from expression have bats in one's belfry, from tendency of bats to fly around erratically. Compare also batshit (“insane”) and squirrelly (“jumpy, eccentric”).
batty · noun2
Batty · proper noun3
From Batte, a Middle English pet-form of Bartholomew.
Etymology from Wiktionary, CC BY-SA 4.0.