noun

injection

in-JEK-shun/ɪnˈdʒekʃn/

The introduction of fluid into the body with a needle.

A clinician gives a patient an injection in the upper arm.

A clinician depresses the plunger of a syringe whose needle is inserted into a patient's exposed upper arm, making the act of injecting liquid immediately visible.

Etymology

inLatininto

+jectLatinto throw

+ionLatinaction or process

The pieces give the image of throwing something in. In medical use, that became forcing fluid into a body, as with a syringe, rather than throwing a solid object.

In context

SCP Orientation4:49

she finds a fresh needle mark with a speck of blood and remembers administering the injection

Your Last First Day (SCP Orientation Tales)

More examples

This medicine is given by injection rather than by mouth.
She needs daily insulin injections to manage her diabetes.
The injection site feels sore for a few hours.

Forms

injection · injections

inject verb — Introduce fluid into the body by needle.

Similar words

shot: An informal term for an injection, often a vaccine.
inoculation: Specifically introduces a vaccine to protect against a disease.