{ Ley"den jar" (lī"d'n jär"; 277). Ley"den phi"al (fī"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.