1590s, "resembling a peach" in color, texture, or some other way, from peach (n.) + -y (2). Slang sense of "attractive" attested by 1900. Extended form peachy-keen recorded from 1953. Related: Peachiness.
Entries linking to peachy
peach n.
c. 1400 peche, peoche, "fleshy fruit of the peach tree" (late 12c. as a surname), from Old French pesche "peach, peach tree" (Old North French peske, Modern French pêche), and directly from Medieval Latin pesca, from Late Latin pessica, variant of persica "peach, peach tree," from Latin mālum Persicum, literally "Persian apple," translating Greek Persikon malon, from Persis "Persia" (see Persian).
Old English had it as persue, persoe, directly from Latin. In ancient Greek Persikos could mean "Persian" or "the peach." The tree is native to China, but reached Europe via Persia. By 1663 William Penn observed peaches in cultivation on American plantations. Meaning "attractive woman" is attested from 1754; that of "good person" is by 1904. Peaches and cream in reference to a type of complexion is from 1901. Peach blossom as the delicate pink hue of the peach blossom is from 1702. Georgia has been the Peach State since 1939, though it was noted as a leading peach-grower by 1908.
-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.