icy adj.

Old English is "ice, piece of ice" (also the name of the Anglo-Saxon rune for -i-), from Proto-Germanic *is- "ice" (source also of Old Norse iss, Old Frisian is, Dutch ijs, German Eis), of uncertain origin; possible relatives are Avestan aexa- "frost, ice," isu- "frosty, icy;" Afghan asai "frost." Slang meaning "diamonds" is attested from 1906.

Modern spelling begins to appear 15c. and makes the word look French. On ice "kept out of the way until wanted" is from 1890. Thin ice in the figurative sense is from 1884. To break the ice "to make the first opening to any attempt" is from 1580s, metaphoric of making passages for boats by breaking up river ice though in modern use it usually has implications of "cold reserve." Ice-fishing is from 1869; ice-scraper is from 1789 in cookery.

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.