AGENT

noun Etymology: Middle English, from Medieval Latin ~-, agens, from Latin, present participle of agere to drive, lead, act, do; akin to Old Norse aka to travel in a vehicle, Greek agein to drive, lead Date: 15th century one that acts or exerts power, 2. something that produces or is capable of producing an effect ; an active or efficient cause, a chemically, physically, or biologically active principle, a means or instrument by which a guiding intelligence achieves a result, one who is authorized to act for or in the place of another: as, a representative, emissary, or official of a government , one engaged in undercover activities (as espionage) ; spy , a business representative (as of an athlete or entertainer) , a computer application designed to automate certain tasks (as gathering information online)