AGENT (2)

A″gent, n. 1. 1. One who exerts power, or has the power to act; an actor.
Heaven made us agents, free to good or ill. Dryden. 2. 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. 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.