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

Molecular motion drives repair In earlier animal studies, a single injection 24 hours after severe injury enabled mice to regain the ability to walk within weeks. —Neetika Walter, Interesting Engineering, 17 Feb. 2026

Neither Jett nor his attorney responded to questions about his offer to connect the Boarmans to his water line, the potential pollution threat of the McCoon well or its missing cement liner and injection data. —Nick Bowlin, The Frontier, 16 Feb. 2026

Other treatments like low-level light therapy, PRP injections, and supplements may also be effective, especially when combined. —Rebecca Strong, USA Today, 16 Feb. 2026

Another method is to use injection-spray bars to create thousands of small holes on a course, using nozzles that force water into the snow. —Los Angeles Times, 15 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