short waves, radio waves whose frequencies range from about 3 to 25 megahertz (Mhz), corresponding roughly to the high-frequency band (see radio frequency). When they impinge on certain layers of the ionosphere, short waves are largely reflected back toward the earth. By one or more reflections between the earth and the ionosphere, a short-wave radio signal can be received at long distances from the transmitter.

Waves (Women Appointed for Voluntary Emergency Service), U.S. navy organization, created (1942) in World War II to release male naval personnel for sea duty. The organization was commanded until 1946 by Mildred Helen McAfee. Waves served in communications, air traffic control, naval air navigation, and clerical positions in the United States, Hawaii, Alaska, and the Caribbean. Recruiting ended in 1945, with a peak enrollment of 86,000. Waves forces were reduced when the war ended. After the passage (1948) of the Women's Armed Service Integration Act, women were enlisted into the regular navy, though they continued to be known as Waves for some time.