Meaning of AGENT in English

[agent] n [ME, fr. ML agent-, agens, fr. L, prp. of agere to drive, lead, act, do; akin to ON aka to travel in a vehicle, Gk agein to drive, lead] (15c) 1: one that acts or exerts power

2. a: something that produces or is capable of producing an effect: an active or efficient cause b: a chemically, physically, or biologically active principle

3: a means or instrument by which a guiding intelligence achieves a result

4: one who is authorized to act for or in the place of another: as a: a representative, emissary, or official of a government "crown ~" "federal ~" b: one engaged in undercover activities (as espionage): spy "secret ~" c: a business representative (as of an athlete or entertainer) "a theatrical ~"

Merriam-Webster English vocab.      Английский словарь Merriam Webster.