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

But Eli Lilly is developing a daily pill called orforglipron, and Amgen is testing a monthly injection called MariTide. —Sarah Zhang, The Atlantic, 28 Nov. 2025

In a state of emergency, Bozok took out a student loan to pay for multiple rounds of PRP injections and nutrition plans. —Leah Dolan, CNN Money, 27 Nov. 2025

The insulin injection device maker fell 6%, adding to its 7% pullback from Tuesday. —Itzel Franco,fred Imbert, CNBC, 26 Nov. 2025

Serious events, such as allergic reactions or injection-site cancers in cats, occur in one in 10,000 to 30,000 cases — far rarer than the deadly diseases vaccines prevent. —Henry I. Miller, Boston Herald, 25 Nov. 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