The Collaborative International Dictionary of English v.0.48:

Cistern \Cis"tern\, n. [OE. cisterne, OF. cisterne, F. cisterne,
   fr. L. cisterna, fr. cista box, chest. See Cist, and cf.
   chest.]
   1. An artificial reservoir or tank for holding water, beer,
      or other liquids.
      [1913 Webster]

   2. A natural reservoir; a hollow place containing water. "The
      wide cisterns of the lakes." --Blackmore.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cistern
    n 1: a sac or cavity containing fluid especially lymph or
         cerebrospinal fluid [syn: cisterna, cistern]
    2: a tank that holds the water used to flush a toilet [syn:
       cistern, water tank]
    3: an artificial reservoir for storing liquids; especially an
       underground tank for storing rainwater

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "cistern":
   artificial lake, bayou lake, dam, dead water, dike, etang,
   farm pond, fishpond, freshwater lake, glacial lake, inland sea,
   lagoon, laguna, lake, lakelet, landlocked water, linn, loch, lough,
   mere, millpond, millpool, nyanza, oxbow lake, plash, pond, pondlet,
   pool, puddle, reservoir, salina, salt pond, stagnant water,
   standing water, still water, sump, tank, tarn, tidal pond,
   volcanic lake, water hole, water pocket, well



Easton's 1897 Bible Dictionary:

Cistern
   the rendering of a Hebrew word _bor_, which means a receptacle
   for water conveyed to it; distinguished from _beer_, which
   denotes a place where water rises on the spot (Jer. 2:13; Prov.
   5:15; Isa. 36:16), a fountain. Cisterns are frequently mentioned
   in Scripture. The scarcity of springs in Palestine made it
   necessary to collect rain-water in reservoirs and cisterns (Num.
   21:22). (See WELL.)

     Empty cisterns were sometimes used as prisons (Jer. 38:6; Lam.
   3:53; Ps. 40:2; 69:15). The "pit" into which Joseph was cast
   (Gen. 37:24) was a _beer_ or dry well. There are numerous
   remains of ancient cisterns in all parts of Palestine.