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

For Tech alums, people who have lived, or do live, in Lubbock now and/or identify with the Red Raiders as their own, this season is a full syringe injection of fun. —Fort Worth Star-Telegram, 1 Jan. 2026

Long defined by high prices, shortages and weekly injections, drugs including Wegovy and Zepbound are expected to be easier to access and afford. —Berkeley Lovelace Jr, NBC news, 1 Jan. 2026

On December 12, 2025, the Federal Reserve validated this instability by initiating a $40 billion monthly liquidity injection to stabilize the banking system. —Katica Roy, Fortune, 31 Dec. 2025

In December, a higher dose of semaglutide, the active ingredient in Wegovy, was approved for weight loss (and the reduction of cardiovascular risks) as a pill instead of an injection. —Matthew Herper, STAT, 31 Dec. 2025

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