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

Explanation

An injection is a shot, or a dose of medicine given by way of a syringe and a needle. When you get jabbed in the arm with a tetanus vaccine, that's an injection. The medical kind of injection forces a small amount of a drug under the skin or directly into a muscle. Other injections are similar in that they involve a liquid being forced by pressure, like the fuel injection in a car, which pushes gasoline directly into the engine. Since the 1600s, injection has been used to mean "forcing a fluid into a body," from the Latin inicere, "to throw in" or "to throw on."

Example Sentences

Several days after the injection, she had to have emergency surgery after showing signs of an ectopic pregnancy rupture.

From Salon • May 26, 2026

The company famously teetered on the edge of bankruptcy in 1996, surviving only through a $5 million cash injection from the Japanese videogame developer Sega.

From MarketWatch • May 23, 2026

But to get EU approval for the cash injection, Berlin promised to eventually reduce its shareholding, and the finance ministry confirmed Tuesday that the sale had begun.

From Barron's • May 19, 2026

Johnson said that Alan gave him a "dopamine injection numerous times a day".

From BBC • May 18, 2026

But the regiment was given an injection of pride and spirit when, on May 4, 1943, they were awarded a new name.

From "A Thousand Sisters" by Elizabeth Wein

Related Words

• dose
• needle