Leyden jar

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. An early form of capacitor consisting of a glass jar lined inside and out with tinfoil and having a conducting rod connected to the inner foil lining and passing out of the jar through an insulated stopper.

Century Dictionary and Cyclopedia

1. n. See jar.

Wiktionary

1. n. A glass jar or bottle used to accumulate static electricity between two electrodes.

GNU Webster's 1913

1. n. (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.

WordNet 3.0

1. n. an electrostatic capacitor of historical interest