WordNet (r) 3.0 (2006):

kilobyte
    n 1: a unit of information equal to 1000 bytes [syn: kilobyte,
         K, KB, kB]
    2: a unit of information equal to 1024 bytes [syn: kilobyte,
       kibibyte, K, KB, kB, KiB]

The Free On-line Dictionary of Computing (30 December 2018):

kilobyte
KB

    (KB) A unit of data equal to 1000 bytes (but see
   binary prefix for other definitions).

   One kilobyte is the amount of data in 1000 ASCII (or UTF-8)
   characters or about 250 English words (whose average length is
   about four characters).

   1000 kilobytes are one megabyte.

   (2014-07-21)