O.E. is "ice," from P.Gmc. *isa- (cf. O.N. iss, O.Fris. is, Du. ijs, Ger. Eis), with no certain cognates beyond Gmc. Slang meaning "diamonds" is attested from 1906. Ice cream is first recorded 1688 (as iced cream); icing in the sugary sense is from 1769; ice cube first recorded 1929. To break the ice "to make the first opening to any attempt" is from 1590, metaphoric of making passages for boats by breaking up river ice though in modern use usually with implications of "cold reserve."