A piece of laboratory equipment used for creating vacuums, often made of glass in a bell-like shape. / A bell-shaped glass used to cover and protect items such as food.

plural of Leyden jar

(electrical engineering, historical) A glass jar or bottle used to accumulate static electricity between two electrodes.

(archaic, medicine) Synonym of cupping glass

plural of jam jar

A glass container for jam. / (Cockney rhyming slang) A car.

A small insulated Leyden jar, placed between an electrical machine and a larger jar or battery, so as to announce, by its repeated discharges, the amount of electricity passed into the larger jar.

plural of unit jar

A jar into which anybody who utters a profanity is obliged to drop some money.

plural of cupping jar