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

Formulations intended for pain treatment include injections and transdermal patches that release the drug gradually through the skin. — Encyclopedia Britannica, 28 Aug. 2026

Adames will rest and rehab after getting a platelet-rich plasma injection Thursday night, and typical recovery takes 3-4 weeks. — Justice Delos Santos, Mercury News, 28 Aug. 2026

In proof-of-concept experiments, the Paraborgs achieved a 95 percent success rate when performing close-range injections from within 15 centimeters of the target. — Jijo Malayil, Interesting Engineering, 27 Aug. 2026

If executed, the agency said Humphreys will be the 55th inmate to be put to death by lethal injection in the state. — Caroline Silva, AJC.com, 27 Aug. 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