A universal joint (also called a universal coupling or U-joint) is a joint or coupling connecting rigid shafts whose axess are inclined to each other. It is commonly used in shafts that transmit rotary motion. It consists of a pair of hingess located close together, oriented at 90° to each other, connected by a cross shaft.   

U-joints are also sometimes called  Cardan joint, Hooke joint , Spicer joint or Hardy Spicer joint.