Meaning

noun the forceful insertion of a substance under pressure

noun any solution that is injected (as into the skin)

noun the act of putting a liquid into the body by means of a syringe

originBorrowed 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 from Wiktionary, CC BY-SA 3.0