heaviside
- n English physicist and electrical engineer who helped develop telegraphic and telephonic communications; in 1902 (independent of A. E. Kennelly) he suggested the existence of an atmospheric layer that reflects radio waves back to earth (1850-1925)
heaviside layer
- n a region of the ionosphere (from 50 to 90 miles up) that reflects radio waves of medium length
heavy hitter
- n an influential person who works hard to promote the causes they are interested in
heavy hydrogen
- n an isotope of hydrogen which has one neutron (as opposed to zero neutrons in hydrogen)
heavy metal
- n a metal of relatively high density (specific gravity greater than about 5) or of high relative atomic weight (especially one that is poisonous like mercury or lead)
- n loud and harsh sounding rock music with a strong beat; lyrics usually involve violent or fantastic imagery
heavy metal music
- n loud and harsh sounding rock music with a strong beat; lyrics usually involve violent or fantastic imagery
heavy particle
- n any of the elementary particles having a mass equal to or greater than that of a proton and that participate in strong interactions; a hadron with a baryon number of +1
heavy spar
- n a white or colorless mineral (BaSO4); the main source of barium
heavy water
- n water containing a substantial proportion of deuterium atoms, used in nuclear reactors