Source : Webster's Revised Unabridged Dictionary (1913)

Jar \Jar\, n. [F. jarre, Sp. jarra, from Ar. jarrah ewer; cf.
   Pers. jarrah.]
   1. A deep, broad-mouthed vessel of earthenware or glass, for
      holding fruit, preserves, etc., or for ornamental
      purposes; as, a jar of honey; a rose jar. --Dryden.

   2. The measure of what is contained in a jar; as, a jar of
      oil; a jar of preserves.

   {Bell jar}, {Leyden jar}. See in the Vocabulary.

Leyden jar \Ley"den jar"\ (l[imac]"d'n j[aum]r"; 277). Leyden
phial \Ley"den phi"al\ (f[imac]"al).(Elec.)
   A glass jar or bottle used to accumulate electricity. It is
   coated with tin foil, within and without, nearly to its top,
   and is surmounted by a brass knob which communicates with the
   inner coating, for the purpose of charging it with
   electricity. It is so named from having been invented in
   Leyden, Holland.

Source : WordNet®

Leyden jar
     n : an electrostatic capacitor of historical interest [syn: {Leiden
         jar}]