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

The roster received a $26 million injection over the course of the summer transfer window. — Daniel Sperry, Kansas City Star, 20 Sep. 2026

In 2022, Rios was back in court facing misdemeanor charges for being under the influence of drugs, possession of heroin and Alprazolam, a benzodiazepine commonly prescribed to treat anxiety or panic disorders, and possession of an injection device. — Hannah Fry, Los Angeles Times, 18 Sep. 2026

Rates of side effects — such as injection-site pain, fatigue and headaches — were more common in the mFlusiva group but still mild to moderate. — Berkeley Lovelace Jr, NBC news, 18 Sep. 2026

Prompt injection, training data poisoning, model manipulation, agent permission abuse and the leakage of sensitive information into unsanctioned tools create new exposures and expand the attack surface. — Rob Sloan, Forbes.com, 18 Sep. 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