Columbia Encyclopedia

Search results

500 results found

sulfide

(Encyclopedia)sulfide, chemical compound containing sulfur and one other element or sulfur and a radical. Sulfides may be salts or esters of hydrogen sulfide, H2S, or may be formed directly, e.g., by heating a meta...

derecho

(Encyclopedia)derecho dərāˈchō [key], a long-lived windstorm over a wide expanse that is associated with a line of rapidly moving thunderstorms or showers. The winds in a derecho generally exceed 57 mph (92 kph...

coercion

(Encyclopedia)coercion, in law, the unlawful act of compelling a person to do, or to abstain from doing, something by depriving him of the exercise of his free will, particularly by use or threat of physical or mor...

contact lens

(Encyclopedia)contact lens, thin plastic lens worn between the eye and eyelid that may be used instead of eyeglasses. Actors, models, and others wear them for appearance, and athletes use them for safety and conven...

organic food

(Encyclopedia)organic food, food raised without chemicals and processed without additives. Under standards adopted by the U.S. Agriculture Dept. (USDA) in 2000 and fully effective in 2002, synthetic fertilizers and...

oxytocin

(Encyclopedia)oxytocin ŏksĭtōˈsĭn [key], hormone released from the posterior lobe of the pituitary gland that facilitates uterine contractions and the milk-ejection reflex. The structure of oxytocin, a cyclic ...

narcolepsy

(Encyclopedia)narcolepsy, a sleep disorder characterized by excessive daytime sleepiness and recurring unwanted episodes of sleep (“sleep attacks”). People with narcolepsy may abruptly fall asleep at almost any...

Pulitzer Prizes

(Encyclopedia)Pulitzer Prizes, annual awards for achievements in American journalism, letters, and music. The prizes are paid from the income of a fund left by Joseph Pulitzer to the trustees of Columbia Univ. They...

Bachelard, Gaston

(Encyclopedia)Bachelard, Gaston gästôNˈ bäshlärˈ [key], 1884–1962, French philosopher. He held degrees in physics, mathematics, and philosophy and taught at Dijon (1930–40) and the Univ. of Paris (1940–...

pulse, in anatomy

(Encyclopedia)pulse, alternate expansion and contraction of artery walls as heart action varies blood volume within the arteries. Artery walls are elastic. Hence they become distended by increased blood volume duri...