Agent

A"gent (?), a. [L. agens, agentis, p. pr. of agere to act; akin to Gr. ? to lead, Icel. aka to drive, Skr. aj. √2.] Acting; -- opposed to patient, or sustaining, action. [Archaic] "The body agent." Bacon.

A"gent, n. 1. One who exerts power, or has the power to act; an actor.

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

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

3. 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.