ETYMOLOGY
for adj.: of obscure origin
for n.1.: from teat () + -y
EXAMPLE
“…but if they loose, though it be but a trifle, two or three games at tables, or a dealing at Cards for 2d a game, they are so cholericke and tetty that no man may speake with them, and breake many times into violent passions, oaths, imprecations, and vnbeseeming speeches, little differing from mad men for the time…”
From: The Anatomy of Melancholy
By Robert Burton, 1621
Lexicophilia 