English Reference
noun

injection

n.
US /ˌɪnˈdʒɛkʃən/ UK /ɪndʒˈɛkʃən/ in·jec·tion UK spelling injection's, injection's

  1. 01 B1 Intermediate Medicine

    the act of putting medicine into your body using a needle and a syringe.

    the administration of a liquid medication or other substance into the body via a needle and syringe.

    Simple

    The nurse gave him an injection in his arm to help with the pain.

    In context

    The patient required a subcutaneous injection of insulin twice daily to manage his blood sugar levels effectively.

    shotjabinoculation
  2. 02 B2 Upper Intermediate

    a large amount of money added to a business or project to help it succeed.

    the provision of a significant amount of capital to an organization to improve its financial health or support a specific project.

    Simple

    The small company survived thanks to a cash injection from a new investor.

    In context

    The government announced a massive injection of funds into the public transport sector to modernize the aging rail infrastructure.

    withdrawaldivestment
  3. 03 B2 Upper Intermediate Technical

    the way fuel is forced into an engine to make it run.

    the pressurized introduction of fuel into the combustion chamber of an internal combustion engine.

    Simple

    Modern cars use electronic fuel injection instead of old-fashioned carburetors.

    In context

    The mechanic explained that a fault in the fuel injection system was causing the engine to stall at high speeds.

  4. 04 C1 Advanced Technical Computing

    the act of putting extra code into a computer program, often to attack it.

    the exploitation of a computer bug by processing invalid data to change the course of execution, such as in a SQL injection attack.

    Simple

    The website was hacked using a common technique called SQL injection.

    In context

    Developers must sanitize all user inputs to prevent malicious code injection that could compromise the database integrity.

  5. 05 C1 Advanced Technical Math

    a rule where every starting value matches to a different result.

    a function that maps distinct elements of its domain to distinct elements of its codomain; a one-to-one mapping.

    Simple

    In this math problem, we need to prove that the function is an injection.

    In context

    The student demonstrated that the mapping was an injection by showing that no two distinct inputs produced the same output value.

    one to one function

It's a twice-a-year injection that is remarkably effective in preventing an HIV infection.

NPR· 13 Aug 2026

It is common to get some swelling, redness or tenderness where you have the injection.

BBC News· 3 Aug 2026

Borrowed from Middle French injection, from Latin iniectio. The mathematical sense is from French injection, introduced by Nicolas Bourbaki in their treatise Éléments de mathématique. Equivalent to inject + -ion.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin French injection
Level C1 · Advanced
Frequency Frequent
Updated