出典:Wiktionary
Uncertain, first attested as teachie in the 1597 first quarto versions of Romeo and Juliet and Richard III. Perhaps coined by Shakespeare. Also variously derived from English tetch (“tantrum, fit of anger”); from Scots tache (“blotch, fault”); from Middle English tatch (“blemish”) &c. under influence from touchy, in turn derived from Old French tache, from proposed Vulgar Latin *tacca, from Gothic (taikns, “sign”), from proposed Proto-Indo-European *deyḱ-.
tetchy (comparative tetchier, superlative tetchiest)