agent

1 something used to achieve an end the whitening agent in the detergent is chlorine bleach the Church has been the traditional agent for social justice in impoverished countries Synonyms agency, instrument, instrumentality, machinery, means, medium, ministry, organ, vehicle Related Words determinant, expedient, factor, influence, ingredient, mechanism, tool; weapon; activator, animator, catalyst, driver, energizer, executor, generator, impetus, incentive, inspiration, instigation, instigator, launcher, mover, power, stimulus, trigger; antecedent, cause, occasion, reason; subagency, subagent

2 a person who acts or does business for another the sports agent negotiated a record-breaking contract for the baseball player Synonyms assignee, attorney, commissary, delegate, deputy, envoy, factor, minister, procurator, proxy, rep, representative Related Words ambassador, diplomat, diplomatist, emissary, foreign minister, legate, plenipotentiary; alternate, backup, pinch hitter, relief, replacement, stand-in, sub, substitute, surrogate, understudy; informer, operative, spy; broker, distributor, manager; arbiter, arbitrator, comprador (or compradore), conciliator, go-between, intercessor, intermediary, interposer, liaison, mediator, middleman, peacemaker; mouthpiece, point man, point person, prophet, speaker, spokesman, spokesperson

3 a person sent on a mission to represent another an undercover agent of the Crown Synonyms ambassador, delegate, emissary, envoy, legate, minister, representativeRelated Words ambassadress; attaché, chargé d'affaires, consul, deputy, diplomat, foreign minister, nuncio, procurator, proxy; apostle, evangelist, missionary; deputation, detachment, legation; courier, messenger; mouthpiece, spokesperson

4 a person who tries secretly to obtain information for one country in the territory of another usually unfriendly country an agent feeding information about enemy troop movements Synonyms spy, asset, emissary, intelligencer, mole, operative, spook, undercoverRelated Words courier; counterspy, double agent, sleeper; infiltrator, informer, stool pigeon; spymaster, superspy