The wheel in an escapement (as of a clock or a watch) into whose teeth the pallets play.

(US) Any assassin bug of the genus Arilus, large true bugs with wheel-shaped pronotal armor. They are predators upon soft-bodied insects.

A press by which railway-car wheels are forced on, or off, their axles.

A pinion with cylindrical staves, instead of teeth, inserted at their ends in two parallel disks or plates.

A device for measuring distance, consisting of a wheel of fixed circumference, a handle, and a clicking device triggered by each revolution of the wheel.

A device for producing straight-line motion from circular motion, on the principle that a pin fastened in the periphery of a gear wheel will describe a straight line when the wheel rolls around inside a fixed internal gear of twice its diameter.

A noria.

(horology) The wheel of an escapement.

(engineering) A form of cam shaped like a heart, used to convert uniform rotary motion into uniform reciprocating motion.

Ferris wheel