Old English is "ice" (also the name of the rune for -i-), from Proto-Germanic *isa- (cf. Old Norse iss, Old Frisian is, Dutch ijs, German Eis), with no certain cognates beyond Germanic, though possible relatives are Avestan aexa- "frost, ice," isu- "frosty, icy;" Afghan asai "frost." Slang meaning "diamonds" is attested from 1906.
Ice cube attested from 1904. Ice age attested from 1832. 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 usually with implications of "cold reserve."