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

Rajpaul's cause of death was listed as homicide due to acute cardiopulmonary dysfunction and intramuscular/intravascular silicone injections. —Becca Longmire, PEOPLE, 10 Oct. 2025

Cammy had a case of the zoomies following her Librela injection, a medication used about once a month to control the pain associated with osteoarthritis in dogs, which was approved by the Food and Drug Administration in 2023, Newsweek previously reported. —Liz O'Connell, MSNBC Newsweek, 10 Oct. 2025

The virus’ genetic sequence was identified and released in January; by May volunteers were receiving injections in the human trials; and in December both Pfizer-BioNTech and Moderna’s vaccines got FDA authorization. —Merrill Fabry, Time, 9 Oct. 2025

The nearly $2 billion injection into Polymarket comes as investors are ponying up cash to capitalize on growing enthusiasm for prediction markets, or arenas where investors can bet on whether China will invade Taiwan or the future price of cryptocurrencies like Bitcoin and Ethereum. —Andrew Nusca, Fortune, 8 Oct. 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