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Agent vs. Reagent: What's the Difference?

Edited by Harlon Moss || By Janet White || Updated on October 18, 2023
"Agent" is a person/thing acting on behalf of another; "Reagent" is a substance used in chemical reactions to detect, measure, or produce other substances.

Key Differences

"Agent" refers to an entity that performs actions or exerts power, often on someone else's behalf, like a representative in business dealings or a force in scientific contexts. Conversely, "Reagent" is specifically utilized within the scientific realm, particularly chemistry, as a substance introduced to bring about a chemical reaction or to see if a reaction occurs.
"Agent" can be a broad term used in various fields, implying a range of roles from a spy to a real estate broker, all acting with a purpose or influence. "Reagent," however, maintains a consistent meaning across contexts, always relating to the role it plays in chemical analysis or reaction.
"Agent" can refer to both animate and inanimate entities, encompassing individuals, groups, or even substances that actively cause something to happen. On the other hand, "Reagent" is exclusively an inanimate term, referring specifically to chemical substances used in laboratory settings.
"Agent" carries a sense of authority, responsibility, or intentionality in its actions, be they physical, social, or biological. In contrast, "Reagent" operates within the confines of chemical interactions, lacking independent authority but critical in facilitating or indicating reactions.
"Agent" is versatile, used metaphorically or literally across disciplines, from literature to politics to biology. "Reagent," however, is a term firmly rooted in the sciences, devoid of metaphorical use, and strictly technical in its application.

Comparison Chart


Representative or force causing an effect
Substance in chemical reactions


Broad: legal, literary, scientific, etc.
Specific: scientific, particularly chemistry


Authority, intention, representation
Technical, analytical

Scope of Use

Versatile across disciplines
Restricted to scientific use


Can be both
Always inanimate

Agent and Reagent Definitions


A person who acts for or represents another.
The author sent her manuscript to her literary agent.


A substance used to cause a chemical reaction.
The scientist added a reagent to test the solution's pH level.


A representative in business transactions.
The agent negotiated a lucrative contract for his client.


A material used in reactions to measure other substances.
She used a reagent to measure the concentration of glucose in the sample.


A spy or secret operative.
The agent covertly gathered intelligence behind enemy lines.


A compound used to detect another substance.
The reagent turned blue, indicating the presence of copper.


One that acts or has the power or authority to act.


An agent for analysis in biochemistry.
The lab stocked reagents for various biochemical analyses.


One empowered to act for or represent another
An author's agent.
An insurance agent.


A substance involved in producing a chemical compound.
A specific reagent was necessary to synthesize the new drug.


A means by which something is done or caused; an instrument.


A substance used in a chemical reaction to detect, measure, examine, or produce other substances.


A force or substance that causes a change
A chemical agent.
An infectious agent.


(chemistry) A compound or mixture of compounds used to treat or test materials, samples, other compounds or reactants in a laboratory or sometimes an industrial setting.


A representative or official of a government or administrative department of a government
An FBI agent.


A substance capable of producing with another a reaction, especially when employed to detect the presence of other bodies; a test.


A spy.


A chemical agent for use in chemical reactions


(Linguistics) The argument that expresses the means or cause of an action or event described by a phrase or clause. The noun John is the agent in the clause John threw the ball.


To act as an agent or representative for
Who will agent your next book?.


To act as an agent or representative.


One who exerts power, or has the power to act


One who acts for, or in the place of, another (the principal), by that person's authority; someone entrusted to do the business of another


A person who looks for work for another person


Someone who works for an intelligence agency


An active power or cause or substance; something (e.g. biological, chemical, thermal, etc.) that has the power to produce an effect


(computing) In the client-server model, the part of the system that performs information preparation and exchange on behalf of a client or server. Especially in the phrase “intelligent agent” it implies some kind of autonomous process which can communicate with other agents to perform some collective task on behalf of one or more humans.


(grammar) The participant of a situation that carries out the action in this situation, e.g. "the boy" in the sentences "The boy kicked the ball" and "The ball was kicked by the boy".


(gambling) A cheat who is assisted by dishonest casino staff.


Acting; - opposed to patient, or sustaining, action.


One who exerts power, or has the power to act; an actor.
Heaven made us agents, free to good or ill.


One who acts for, or in the place of, another, by authority from him; one intrusted with the business of another; a substitute; a deputy; a factor.


An active power or cause; that which has the power to produce an effect, such as a physical, chemical, or medicinal agent; as, heat is a powerful agent.


A chemical substance having biological effects; a drug.


An active and efficient cause; capable of producing a certain effect;
Their research uncovered new disease agents


A substance that exerts some force or effect


A representative who acts on behalf of other persons or organizations


A businessman who buys or sells for another in exchange for a commission


Any agent or representative of a federal agency or bureau


The semantic role of the animate entity that instigates or causes the hapening denoted by the verb in the clause


An entity that brings about a result.
Water is the agent responsible for the rock's erosion.


A person or thing that exerts power.
He was a free agent, acting entirely of his own volition.


Is a "reagent" always chemical?

Yes, reagents are substances used in chemical reactions or analyses.

Do "agents" have to be authorized?

Often, especially when representing others, but not always in every context.

Is "agent" used in biology?

Yes, for entities causing effects, like "change agents" or "bioactive agents."

Can an "agent" be non-human?

Yes, "agent" can refer to anything causing an effect, even non-living things.

Are "reagents" used in everyday products?

They're more common in labs but can be in products, like testing kits.

Is "agent" a legal term?

It can be, as in "power of attorney" or "agent of service."

Does "agent" imply autonomy?

Not always; agents can act independently or under direction.

Can "reagents" be natural substances?

Yes, if they cause or indicate a chemical reaction.

Are "reagents" safe to handle?

It depends on the chemical; some are safe, others require careful handling.

Can an "agent" act for multiple parties?

Typically, agents represent one principal, but exceptions exist, like in brokerage.

What's a "universal reagent"?

A substance that reacts with many others, used across multiple reactions.

Are all "agents" intermediaries?

Often, but not always; the term is broad and used in various contexts.

Do "reagents" change composition?

They can, especially when they react with other substances.

Are "reagents" used in medicine?

Yes, frequently in testing and research.

Are "reagents" specific to reactions?

Often, as different reactions require different reagents.

How are "reagents" stored?

Often in controlled environments, like cool, dark places, depending on sensitivity.

Is an "agent" responsible for outcomes?

In many cases, yes, especially when representing others or causing effects.

Can "agents" be virtual or digital?

Yes, like in software agents in technology.

Can "agent" imply undercover work?

Yes, especially in contexts like espionage or law enforcement.

Can "reagents" expire?

Yes, many have a shelf life after which their effectiveness decreases.
About Author
Written by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.
Edited by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.

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