A system of television cameras, connected by cable to a control room, used for surveillance.

The "internal body clock" that regulates the (roughly) 24-hour cycle of biological processes in animals and plants.

Any of the global circulatory currents, such as the Gulf Stream, that are driven by differences in temperature and salinity.

An itinerant preacher, especially a Methodist. / (US) A judge who holds court in a series of towns. / (computing) A computer consultant who advises non-profit organizations.

The parallel of latitude that runs 66° 33′ 39″ north of the Equator, which marks approximately the southernmost place in the Northern Hemisphere where the sun does not set on the summer solstice and does not rise on the winter solstice.

(biology) of, relating to, or showing rhythmic behaviour with a period of 24 hours; especially of a biological process

(countable) A specific system of electrical circuits in a particular device; (uncountable) the design of such a system.

(intransitive) to move in circles or through a circuit / (transitive) to cause (a person or thing) to move in circles or through a circuit / to move from person to person, as at a party

A small circle. / A ring (typically of gold or silver) worn as an ornament on the head. / A crown without arches or a covering. / A round body; an orb.

A circular arena in a circus, where the acts are performed.