injection

noun

in·​jec·​tion in-ˈjek-shən How to pronounce injection (audio)
Synonyms of injectionnext
1
a
: 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.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Participants were randomly assigned to receive either the vaccine with pembrolizumab or placebo injections alongside the immune treatment. — Mike McRae 25, New Atlas, 26 Oct. 2026 Side effects of the vaccine included pain around the injection site and a mild fever — similar to those seen with Covid vaccines. — David Cox, NBC news, 23 Oct. 2026 Orion was now approaching its closest point to our planet, roughly 100 miles (160 km) above the surface, ahead of the crucial translunar injection (TLI) burn that would send the astronauts moonward. — Daisy Dobrijevic, Space.com, 22 Oct. 2026 The different categories of wellness providers range from high-intensity interval studios to specialty clinics offering vitamin injections. — Fort Worth Star-Telegram, 22 Oct. 2026 See All Example Sentences for injection

Word History

First Known Use

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

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

Phrases Containing injection

Rhymes for injection

See All Rhymes for injection

Browse Nearby Words

injectant
injection
injection gneiss
See all Nearby Words

Cite this Entry

“Injection.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/injection. Accessed 27 Oct. 2026.

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Kids Definition

injection

noun
in·​jec·​tion in-ˈjek-shən How to pronounce injection (audio)
1
: an act or instance of injecting
2
: something (as a medical drug) that is injected

Medical Definition

injection

noun
in·​jec·​tion in-ˈjek-shən How to pronounce injection (audio)
1
a
: 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

More from Merriam-Webster on injection

Thesaurus: All synonyms and antonyms for injection

Britannica.com: Encyclopedia article about injection

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