agent Definition

agent
noun

1a. Someone who represents an organization and acts on its behalf;
1b. Someone who deals with someone else's business matters, etc.
2. A spy.

Thesaurus: representative, executor, intermediary, surrogate, envoy, go-between, broker, promoter, assistant, attorney, appointee.
Form: secret agent (also)
3. A substance that produces a particular effect.
4. Someone who is the cause of something.
5. grammar.
The person who performs an action, eg the subject of an active verb or noun, etc preceded by by in a passive construction.

Etymology: 16c: from Latin agens, from agere to do.