Source : Webster's Revised Unabridged Dictionary (1913)

Quantum \Quan"tum\, n.; pl. {Quanta}. [L., neuter of quantus how
   great, how much. See {Quantity},]
   1. Quantity; amount. ``Without authenticating . . . the
      quantum of the charges.'' --Burke.

   2. (Math.) A definite portion of a manifoldness, limited by a
      mark or by a boundary. --W. K. Clifford.

   {Quantum meruit}[L., as much as he merited] (Law), a count in
      an action grounded on a promise that the defendant would
      pay to the plaintiff for his service as much as he should
      deserve.

   {Quantum sufficit}, or {Quantum suff.}

Source : WordNet®

quantum
     n 1: a discrete amount of something that is analogous to the
          quantum in quantum theory
     2: (physics) the smallest discrete quantity of some physical
        property that a system can possess (according to quantum
        theory)
     [also: {quanta} (pl)]

Source : Free On-Line Dictionary of Computing

quantum
     
        {time slice}