What does injection mean?
An injection is the act of introducing a substance into a body or another system, most commonly by means of a syringe. In medical contexts, it can refer either to the procedure itself or to a measured dose of medicine given that way, as in a flu injection. The word also has technical uses in engineering, where fuel injection refers to the delivery of fuel into an engine, and in computing, where code or data may be inserted into a system without authorization or in a way that causes unintended behavior. Its defining idea is deliberate insertion: something is introduced into a body, machine, or information environment. Although the medical sense is the most familiar in everyday speech, the broader technical meanings are well established and useful for describing the movement or placement of material through controlled systems.
The introduction of a substance into the body, especially by syringe, or a dose administered in this way.
"The injection took several minutes to relieve the pain."
The medical sense is countable and commonly used in combinations such as “flu injection” and “booster injection.”
The act of introducing a substance, code, or other material into a system, machine, or environment.
"The software update prevented a malicious code injection."
This broader sense is common in technical, engineering, and computing contexts.
Usually countable when referring to individual medical procedures, doses, or instances of inserting material into a system.
"The nurse prepared two injections for the patient."
From a medical jab to a cyberattack, an injection is anything deliberately pushed into a system.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of injection
The word comes from Latin injectio, a noun derived from injicere, meaning “to throw or put into.” That verb combines in- (“into”) with jacere, “to throw,” and is related to a family of English words including eject, reject, project, and deject. The English form appeared in the 17th century and initially referred to the act or process of putting something in, especially into the body. The modern medical sense developed as injections became a standard means of administering medicines.
Related word forms
How injection is actually used
In medicine, the term is often used for an injection containing a medicine, such as a flu injection or a steroid injection. In computing, it commonly occurs in expressions such as code injection, SQL injection, and fuel injection, where the technical sense may be specialized rather than bodily.
Easily confused with injection
An injection introduces a substance into the body, often quickly and through a syringe, whereas an infusion delivers a liquid steadily over a longer period, commonly through an intravenous drip.
Injection specifically involves introducing a substance into a body or system, while insertion is the broader act of putting something into a space or arrangement.