Noun

(en noun)

The person, place or thing from which something (information, goods, etc.) comes or is acquired.

* {{quote-book, year=2006, author=(Edwin Black)

, title=Internal Combustion, chapter=2 citation , passage=More than a mere source of Promethean sustenance to thwart the cold and cook one's meat, wood was quite simply mankind's first industrial and manufacturing fuel.}}

* {{quote-magazine, date=2013-07-06, volume=408, issue=8843, page=68, magazine=(The Economist)

, title= The rise of smart beta , passage=Investors face a quandary. Cash offers a return of virtually zero in many developed countries; government-bond yields may have risen in recent weeks but they are still unattractive. Equities have suffered two big bear markets since 2000 and are wobbling again. It is hardly surprising that pension funds, insurers and endowments are searching for new sources of return.}}

Spring; fountainhead; wellhead; any collection of water on or under the surface of the ground in which a stream originates.

* {{quote-magazine, date=2013-08-16, author= John Vidal

, volume=189, issue=10, page=8, magazine=(The Guardian Weekly) , title= Dams endanger ecology of Himalayas , passage=Most of the Himalayan rivers have been relatively untouched by dams near their sources . Now the two great Asian powers, India and China, are rushing to harness them as they cut through some of the world's deepest valleys.}}

A reporter's informant.

(computing) Source code.

(electronics) The name of one terminal of a field effect transistor (FET).

Noun

(en noun)

One who exerts power, or has the power to act; an actor.

Heaven made us agents , free to good or ill. --Dryden.

One who acts for, or in the place of, another (the principal), by authority from him; one intrusted with the business of another; a substitute; a deputy; a factor.

I see in him [Moby Dick] outrageous strength, with an inscrutable malice sinewing it. That inscrutable thing is chiefly what I hate; and be the white whale agent , or be the white whale principal, I will wreak that hate upon him. --Herman Melville, , ch. 36

An active power or cause; that which has the power to produce an effect; as, a physical, chemical, or medicinal agent ; as, heat is a powerful agent.

(computing) In the client-server model, the part of the system that performs information preparation and exchange on behalf of a client or server. Especially in the phrase “intelligent agent” it implies some kind of autonomous process which can communicate with other agents to perform some collective task on behalf of one or more humans.

(grammar) The participant of a situation that carries out the action in this situation, e.g. "the boy" in the sentences "The boy kicked the ball" and "The ball was kicked by the boy".