Origin: Latin suffix -tion
Injection has 4 different meanings across 1 category:
the forceful insertion of a substance under pressure
"The nurse administered the emergency medicine via injection, delivering the fluid forcefully into his vein to save his life."
The act of injecting, or something that is injected.
"The doctor administered a quick injection to stop my fever from rising."
In plain English: An injection is when a liquid medicine goes straight into your body through a needle.
"She received an injection at the doctor's office to prevent the flu."
Usage: Use "injection" to describe the medical procedure of administering medicine via a needle or any instance where a substance is forcibly introduced into something else. It refers specifically to the act itself or the material being delivered, not the result or the feeling experienced afterward.
The word "injection" comes from the Latin iniectio via Middle French and originally referred to the act of pouring or thrusting something into a container. While it retains this core meaning in general usage, its specific mathematical sense was introduced by Nicolas Bourbaki in their treatise Éléments de mathématique.