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

James Broadnax, 37, is scheduled to be put to death by lethal injection on April 30 in Huntsville. —Jamie Landers, Dallas Morning News, 9 Mar. 2026

While one sometimes can stop giving these injections, most usually require a lifetime of shots usually monthly. —Dr. John De Jong, Boston Herald, 8 Mar. 2026

With Ngumoha starting on the left and Gakpo shifted into the middle (16-goal top scorer Hugo Ekitike was rested with an eye on Tuesday’s Champions League round of 16 first leg away to Galatasaray of Turkey), Liverpool’s attack benefited from an injection of greater energy and dynamism. —James Pearce, New York Times, 7 Mar. 2026

Photos of red, itchy patches at the drug’s injection site (and even more serious claims of itchy patches all over the body) are being shared on Reddit and every social feed. —Audrey Noble, Vogue, 6 Mar. 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