The Collaborative International Dictionary of English v.0.48:

capacitance \ca*pac"i*tance\ (k[.a]*p[a^]s"[i^]*tans), n.
   1. an electrical phenomenon whereby an electric charge is
      stored.

   Syn: electrical capacity, capacity.
        [WordNet 1.5]

   2. (Electronics) a measure of the ability of a capacitor to
      store electrical charge; the ratio of the charge on one
      plate of a capacitor to the potential difference between
      the plates.
      [PJC]

WordNet (r) 3.0 (2006):

capacitance
    n 1: an electrical phenomenon whereby an electric charge is
         stored [syn: capacitance, electrical capacity,
         capacity]
    2: an electrical device characterized by its capacity to store
       an electric charge [syn: capacitor, capacitance,
       condenser, electrical condenser]