K2  abbr. (also k.) 1 kelvin(s). 2 king, king's. 3 köchel (catalogue of mozart's works). 4 (also k) (prec. By a numeral) a computing unit of 1,024 (i.e. 210) bytes or bits, or loosely 1,000. B 1,000. [sense 4 as abbreviation of *kilo-]