(education, historical) The system of home study established in connection with the summer schools assembled at Chautauqua, New York, by the Methodist Episcopal bishop John Heyl Vincent.

(historical) A haulage system for canal boats, in which an electric locomotive running on a monorail has its adhesion materially increased by the pull of the tow rope on a series of inclined gripping wheels.

(historical) A system used by the US Navy in the late 19th century to enable ship-to-ship communications at night. Each installation used a series of eight double lamps (four red and four white) hung from a mast and used to transmit visual codes.

(historical) A system of prison discipline involving periods of confinement to one's cell, associated imprisonment under the mark system, restraint intermediate between imprisonment and freedom, and liberation on ticket of leave.

(historical) A system for identifying people by a physical description based upon anthropometric measurements, notes of markings, deformities, skin colour, impression of thumb lines, etc.

(baseball) A method of sharing playing time, whereby two players are selected to play a single defensive position.

plural of writing system

(linguistics) A system for writing one or more languages; a particular alphabetic, syllabic, logographic, or other scheme. For example, the Latin alphabet or the Cyrillic alphabet.

plural of ring system

(astronomy) Two gravitationally connected stars or other celestial objects which orbit around their center of mass.