[AS.] A moving ridge or swell on the surface of water. Waves in deep water move onward, but the water of which they are composed is continually changing. Scoresby gave 600 feet as the maximum length of sea waves. In 1888 the Umbria was struck by a wave 50 feet high. - Heat, sound, and light are supposed to travel in waves. The wave theory of light regards its phenomena as due to transverse waves in an ethereal medium, their amplitude causing brightness of light, and their frequency causing its color. The colors of the spectrum are estimated to result from various rapidities of vibration, ranging from 459 to 727 millions of millions per second.