Fraternity and sorority, in American colleges, a student society formed for social purposes, into which members are initiated by invitation and occasionally by a period of trial known as hazin...

Great Smoky Mountains, part of the Appalachian system, on the N.C.–Tenn. border; highest range E of the Mississippi and one of the oldest uplands on earth. The mountains are named for the smok...

Aureole, in physics, luminous circle seen when the sun or other bright light is observed through a diffuse medium, i.e., smoke, thin cloud, fog, haze, or mist. It sometimes occurs as a series ...

Laki, volcano, 2,684 ft (818 m) high, S Iceland, at SW edge of the Vatnajökull glacier. Its eruption in 1783 was one of the more devastating on record, leading to the deaths of a quarter of Ic...

Burke, Kenneth Duva, 1897–1993, American critic, b. Pittsburgh, Pa. He was music critic for The Dial (1927–29) and The Nation (1934–36). A profound thinker whose writings have influenced other...

Pasqueflower, name for two similar perennials of the family Ranunculaceae (buttercup family). The Old World pasqueflower (Anemone pulsatilla) was so named because it blossoms around the Easter...

Inness, George, 1825–94, American landscape painter, b. Newburgh, N.Y. His father intended Inness to be a grocer, but he showed artistic talent at an early age and was apprenticed to an engrav...

Dust, atmospheric, minute particles slowly settling or suspended by slight currents and existing in varying amounts in all air. There is least dust at high levels over the ocean and most at lo...

Sexual harassment, in law, verbal or physical behavior of a sexual nature, aimed at a particular person or group of people, especially in the workplace or in academic or other institutional se...

Mass extinction, the extinction of a large percentage of the earth's species, opening ecological niches for other species to fill. There have been at least ten such events. The five greatest w...