agent
n.
late 15c., "one who acts," from Latin agentem (nominative agens) "effective, powerful," present participle of agere "to set in motion, drive, lead, conduct" (see act, n.). Meaning "any natural force or substance which produces a phenomenon" is from 1550s. Meaning "deputy, representative" is from 1590s. Sense of "spy, secret agent" is attested by 1916.
adj.
1610s, from agent, n..
〔李〕[ag =to do做；-ent ⇒“one that does sth. for another为他人做事者”→] n. a person or company that acts for another代理人；代理商