Origin and history of crispy

Old English crisp "curly, crimped, wavy" (of hair, wool, etc.) from Latin crispus "curled, wrinkled, having curly hair," from PIE root *sker- (2) "to turn, bend."

It began to mean "brittle" 1520s, for obscure reasons, perhaps based on what happens to flat things when they are cooked. Sense of "neat, brisk, having a fresh appearance" (1814) is perhaps a figurative use, or perhaps a separate word. Of air, "chill, bracing" by 1869.

As a noun from mid-14c., originally the name of a light, crinkly material formerly used for kerchiefs, veils, etc.; late 14c. as a kind of pastry. By 1826 as "overdone piece of anything cooked" (as in burned to a crisp). Potato crisps (now the British version of U.S. potato chips, but not originally exclusively British) is by 1897; as simply crisps by 1935. In U.S., crisps began to be used by 1903 in trade names of breakfast cereals. Related: Crisply; crispness.

very common adjective suffix, "full of, covered with, or characterized by" the thing expressed by the noun, Middle English -i, from Old English -ig, from Proto-Germanic *-iga-, from PIE -(i)ko-, adjectival suffix, cognate with elements in Greek -ikos, Latin -icus (see -ic). Germanic cognates include Dutch, Danish, German -ig, Gothic -egs.

It was used from 13c. with verbs (drowsy, clingy), and by 15c. with other adjectives (crispy). Chiefly with monosyllables; with more than two the effect tends to become comedic.

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Variant forms in -y for short, common adjectives (vasty, hugy) helped poets after the loss of grammatically empty but metrically useful -e in late Middle English. Verse-writers adapted to -y forms, often artfully, as in Sackville's "The wide waste places, and the hugy plain" (and the huge plain would have been a metrical balk).

After Coleridge's criticism of it as archaic artifice, poets gave up stilly (Moore probably was last to make it work, with "Oft in the Stilly Night"), paly (which Keats and Coleridge himself had used) and the rest.

Jespersen ("Modern English Grammar," 1954) also lists bleaky (Dryden), bluey, greeny, and other color words, lanky, plumpy, stouty, and the slang rummy. Vasty survives, he writes, only in imitation of Shakespeare; cooly and moisty (Chaucer, hence Spenser) he regards as fully obsolete. But in a few cases he notes (haughty, dusky) they seem to have supplanted shorter forms.