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See more synonyms for agent on Thesaurus.com
  1. a person or business authorized to act on another's behalf: Our agent in Hong Kong will ship the merchandise. A best-selling author needs a good agent.
  2. a person or thing that acts or has the power to act.
  3. a natural force or object producing or used for obtaining specific results: Many insects are agents of fertilization.
  4. an active cause; an efficient cause.
  5. a person who works for or manages an agency.
  6. a person who acts in an official capacity for a government or private agency, as a guard, detective, or spy: an FBI agent; the secret agents of a foreign power.
  7. a person responsible for a particular action: Who was the agent of this deed?
  8. Grammar. a form or construction, usually a noun or noun phrase, denoting an animate being that performs or causes the action expressed by the verb, as the police in The car was found by the police.
  9. Indian agent.
  10. a representative of a business firm, especially a traveling salesperson; canvasser; solicitor.
  11. Chemistry. a substance that causes a reaction.
  12. Pharmacology. a drug or chemical capable of eliciting a biological response.
  13. Pathology. any microorganism capable of causing disease.
  14. British. a campaign manager; an election agent.
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  1. acting; exerting power (opposed to patient).
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verb (used with object)
  1. to represent (a person or thing) as an agent; act as an agent for: to agent a manuscript; Who agented that deal?
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Origin of agent

1570–80; < Latin agent- (stem of agēns (present participle) doing), equivalent to ag- (root of agere to do) + -ent- -ent
Related formscoun·ter·a·gent, nounin·ter·a·gent, nounsu·per·a·gent, nounun·der·a·gent, noun

Synonyms for agent

See more synonyms for on Thesaurus.com
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for counteragent

enemy, competitor, candidate, foe, rival, player, challenger, opposition, aspirant, adversary, cure-all, fix, drug, redress, therapy, treatment, antidote, medicine, panacea, pill

Examples from the Web for counteragent

Historical Examples of counteragent

  • It would serve F right if they perfected a counteragent first.

    Greener Than You Think

    Ward Moore

  • Good Lord, it might have contained a counteragent that could have killed me!

    A Knyght Ther Was

    Robert F. Young

  • If I had a counteragent to the grass ready I would not be wasting time talking to reporters.

  • I am on the way to develop the counteragent, but to advance further I need to make tests upon the living grass itself.

  • PM on the wireless with the assurance a counteragent will be perfected within the week.

British Dictionary definitions for counteragent


  1. a person who acts on behalf of another person, group, business, government, etc; representative
  2. a person or thing that acts or has the power to act
  3. a phenomenon, substance, or organism that exerts some force or effecta chemical agent
  4. the means by which something occurs or is achieved; instrumentwind is an agent of plant pollination
  5. a person representing a business concern, esp a travelling salesman
  6. British short for estate agent
  7. short for secret agent
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Derived Formsagential (eɪˈdʒɛnʃəl), adjective

Word Origin for agent

C15: from Latin agent-, noun use of the present participle of agere to do
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for counteragent



1610s, from agent (n.).

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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.

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Online Etymology Dictionary, © 2010 Douglas Harper

counteragent in Medicine


  1. A force or substance, such as a chemical, that causes a change.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

counteragent in Science


  1. A substance that can bring about a chemical reaction or a biological effect. Compare reagent.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.