injection

American  

[in-jek-shuhn] / ɪnˈdʒɛk ʃən /

noun

1. the act of injecting.

2. something that is injected.

3. a liquid injected into the body, especially for medicinal purposes, as a hypodermic or an enema.

4. state of being hyperemic or bloodshot.

5. Mathematics. a one-to-one function.

6. Also called insertion.  Aerospace. the process of putting a spacecraft into orbit or some other desired trajectory.

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injection British  

/ ɪnˈdʒɛkʃən /

noun

1. fluid injected into the body, esp for medicinal purposes

2. something injected

3. the act of injecting

4. 1. the act or process of introducing fluid under pressure, such as fuel into the combustion chamber of an engine

   2. ( as modifier )

      injection moulding

5. maths a function or mapping for which f( x ) = f( y ) only if x = y See also surjection bijection

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injection Scientific  

/ ĭn-jĕk′shən /

1. A substance that is introduced into a organism, especially by means of a hypodermic syringe, as a liquid into the veins or muscles of the body.

2. A function that maps each member of one set (the domain) to exactly one member of another set (the range).

3. Compare bijection surjection

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Other Word Forms

• injective adjective
• postinjection adjective
• reinjection noun
• superinjection noun

Etymology

Origin of injection

First recorded in 1535–45, injection is from the Latin word injectiōn- (stem of injectiō ). See inject, -ion

Example Sentences

Hansen then described the translunar injection burn -- a maneuver that brought Orion within 200 kilometers of Earth before swinging around onto a new course for the Moon.

From Barron's • Apr. 4, 2026

The goal is to make sure everything is working before the craft attempts what is called the translunar injection.

From The Wall Street Journal • Apr. 2, 2026

Lilly is also developing a highly efficacious injection called retatrutide that targets GIP and GLP-1 — both of which are activated by tirzepatide — in addition to glucagon.

From MarketWatch • Apr. 1, 2026

Fellow participant Sarah Reeve, who has limited mobility with her hands, said these sessions had given her an "injection of creativity".

From BBC • Mar. 28, 2026

Francie worked up a fever that night and the site of the injection itched painfully.

From "A Tree Grows in Brooklyn" by Betty Smith

Related Words

• dose
• needle