[ in-jek-shuhn ]
See synonyms for injection on
  1. the act of injecting.

  2. something that is injected.

  1. a liquid injected into the body, especially for medicinal purposes, as a hypodermic or an enema.

  2. state of being hyperemic or bloodshot.

  3. Mathematics. a one-to-one function.

  4. Also called insertion. Aerospace. the process of putting a spacecraft into orbit or some other desired trajectory.

Origin of injection

First recorded in 1535–45, injection is from the Latin word injectiōn- (stem of injectiō). See inject, -ion

Other words from injection

  • post·in·jec·tion, adjective
  • re·in·jec·tion, noun
  • su·per·in·jec·tion, noun

Words Nearby injection Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use injection in a sentence

British Dictionary definitions for injection


/ (ɪnˈdʒɛkʃən) /

  1. fluid injected into the body, esp for medicinal purposes

  2. something injected

  1. the act of injecting

    • the act or process of introducing fluid under pressure, such as fuel into the combustion chamber of an engine

    • (as modifier): injection moulding

  2. maths a function or mapping for which f(x) = f(y) only if x = y: See also surjection, bijection

Derived forms of injection

  • injective, adjective

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for injection


[ ĭn-jĕkshən ]

  1. A substance that is introduced into a organism, especially by means of a hypodermic syringe, as a liquid into the veins or muscles of the body.

  2. A function that maps each member of one set (the domain) to exactly one member of another set (the range). Compare bijection surjection.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.