GNU Collaborative International Dictionary of English

Found 2 definitions 

  1.       

    Agent , 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.

    1913 Webster
    
      
    
  2.       

    Agent, n.
    1. One who exerts power, or has the power to act; an actor.
      1913 Webster
      Heaven made us agents, free to good or ill.
      Dryden.

      1913 Webster
    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.
      1913 Webster
    3. An active power or cause; that which has the power to produce an effect, such as a physical, chemical, or medicinal agent; as, heat is a powerful agent.
      1913 Webster
    4. (Biochem., Med.) a chemical substance having biological effects; a drug.
      PJC