"inclined to pout; sullen, petulant," 1833, from pout + -y (2). Related: Poutiness. An earlier adjective was pouting (1560s).
Entries linking to pouty
pout v.
"thrust out the lips, as in sullenness or displeasure," mid-14c., of uncertain origin, perhaps from Scandinavian (compare Swedish dialectal puta "to be puffed out"), or Frisian (compare East Frisian püt "bag, swelling," Low German puddig "swollen"); related via notion of "inflation" to Old English ælepute "fish with inflated parts," Modern English pout as a fish name, and Middle Dutch puyt, Flemish puut "frog," all from a hypothetical PIE imitative root *beu- suggesting "swelling" (see bull (n.2)). Also compare French bouder "to pout," also presumably imitative (and the source of boudoir). Related: Pouted; pouting.
As a noun from 1590s; "a protrusion of the lips as in pouting; a fit of sullenness or displeasure."
-y 2
adjective suffix, "full of or characterized by," from Old English -ig, from Proto-Germanic *-iga- (source also of Dutch, Danish, German -ig, Gothic -egs), from PIE -(i)ko-, adjectival suffix, cognate with elements in Greek -ikos, Latin -icus (see -ic). Originally added to nouns in Old English; used from 13c. with verbs, and by 15c. even with other adjectives (for example crispy). Adjectives such as hugy, vasty are artificial words that exist for the sake of poetical metrics.