injection

noun

in·​jec·​tion in-ˈjek-shən 

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

But that last-milisecond injection means little fuel vaporization, so the fuel burns dirty and often not completely. —New Atlas, 23 Feb. 2026

Zepbound injection pen arranged in the Brooklyn borough of New York on March 28, 2024. —Annika Kim Constantino, CNBC, 23 Feb. 2026

While it can be delivered transdermally through the skin as a patch, alternative forms of estrogen therapy include pills, gels, injections and vaginal inserts. —Jacqueline Howard, CNN Money, 23 Feb. 2026

The Food and Drug Administration approved a label expansion allowing Zepbound to be delivered through the four-dose, single-patient KwikPen, which provides four once-weekly injections without the need for syringes. —Shafiq Najib, ABC News, 23 Feb. 2026

Word History

First Known Use

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

Phrases Containing injection

• fuel injection
• hypodermic injection
• injection molding

Rhymes for injection

• abjection
• advection
• affection
• bijection
• bisection
• collection
• complexion
• confection
• connection
• connexion
• convection
• correction

Kids Definition

injection

noun

in·​jec·​tion in-ˈjek-shən 

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 

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