E-mail:
  Short for 'electronic mail,' a form of Internet communication that provides computer users with a convenient and highly efficient method of wasting the hundreds of working hours saved annually by the introduction of data-processing systems.

Entropy:
  The tendency of everything in the universe to end up being owned by Bill Gates.

Fragmentation:
  Tendency   for      parts   of     the same  file to     be scattered over    non continuous sectors of a disk, which can cause long waits for files to be read.

Mnemonic:
  An acronym, rhyme, or other memory aid,. Ironically, there is no known recollection-enhancing device that has helped anyone remember how to spell 'mnemonic.'