noun

1. a person or thing that performs an action or brings about a certain result, or that is able to do so
2. an active force or substance producing an effect a chemical agent
3. a person, firm, etc. empowered to act for another
4. ☆ a representative of a government agency revenue agent
5. ☆ Informal a traveling salesperson
6. Gram. the word or words designating the person or thing that performs the action of the verb in a sentence

Etymology: L agens (gen. agentis), prp. of agere, act

intransitive verb, transitive verb