a·gen·cy 
(ājən-sē)
(ājən-sē)n. pl. a·gen·cies
1. The condition of being in action; operation.
2. The means or mode of acting; instrumentality.
3.
a. A business with agents that negotiate deals for clients: a talent agency; a real estate agency.
b. An advertising or public relations firm.
4. An administrative division of a government or international body.
[Medieval Latin agentia, from Latin agēns, agent-, present participle of agere, to do; see AGENT.]