in·​jec·​tion | \ in-ˈjek-shən How to pronounce injection (audio) \

Definition of injection

1a : an act or instance of injecting
b : the placing of an artificial satellite or a spacecraft into an orbit or on a trajectory also : the time or place at which injection occurs
2 : something (such as a medication) that is injected
3 : a mathematical function that is a one-to-one mapping — compare bijection, surjection

Examples of injection in a Sentence

The medicine cannot be taken orally; it must be given by injection. an injection of a painkiller The struggling company needed an injection of cash.
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Recent Examples on the Web Pfizer already intentionally shrank the dose: Adults have been getting 30 micrograms of mRNA in each injection; in the under-5s, the company is trying three micrograms apiece. Katherine J. Wu, The Atlantic, 21 Jan. 2022 The right injection point is not necessarily the FedEx sort center closest to the customer. Steve Banker, Forbes, 20 Jan. 2022 Hormones that can ease period pain can also be given through an injection, skin patch, implant (placed under the skin on your arm), vaginal ring, or IUD. Claire Gillespie,, 19 Jan. 2022 Game developer Sky Mavis, play-to-earn gaming guild Yield Guild Games, investment firm Avenir and the founders of Chipper Cash also participated in the capital injection. Georg Szalai, The Hollywood Reporter, 19 Jan. 2022 Informing people that the flu shot cannot cause the flu or that the MMR injection is safe for children may make vaccine skeptics even more hesitant. Taylor Dotson, The Conversation, 18 Jan. 2022 Boyd also operates an injection-molding facility in Beaverton. Mike Rogoway | The Oregonian/oregonlive, oregonlive, 18 Jan. 2022 Attorneys for the inmates had asked for the executions to be delayed pending a late February trial on the constitutionality of the lethal injection protocol. Paul P. Murphy, CNN, 14 Jan. 2022 The Oklahoma Department of Corrections does not currently have execution protocols in place for any method other than lethal injection. Fox News, 12 Jan. 2022

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'injection.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of injection

15th century, in the meaning defined at sense 1a

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Time Traveler for injection

Time Traveler

The first known use of injection was in the 15th century

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Dictionary Entries Near injection



injection gneiss

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Last Updated

27 Jan 2022

Cite this Entry

“Injection.” Dictionary, Merriam-Webster, Accessed 28 Jan. 2022.

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More Definitions for injection



English Language Learners Definition of injection

: the act or process of forcing a liquid medicine or drug into someone or something by using a special needle
: the act or process of forcing a liquid into something
: the addition of something (such as money) that is needed to support something


in·​jec·​tion | \ in-ˈjek-shən How to pronounce injection (audio) \

Kids Definition of injection

: an act or instance of forcing a fluid (as a medicine) into a part of the body by using a special needle Insulin can be given by injection.


in·​jec·​tion | \ in-ˈjek-shən How to pronounce injection (audio) \

Medical Definition of injection

1a : the act or an instance of injecting a drug or other substance into the body
b : a solution (as of a drug) intended for injection (as by catheter or hypodermic syringe) either under or through the skin or into the tissues, a vein, or a body cavity
c : an act or process of injecting vessels or tissues also : a specimen prepared by injection
2 : the state of being injected : congestion — see circumcorneal injection


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