v (transitive) To push or pump (something, especially fluids) into a cavity or passage.
v (transitive) To introduce (something) suddenly or violently.
v (transitive) To administer an injection to (someone), especially of medicine or drugs.
v (intransitive) To take or be administered something by means of injection, especially medicine or drugs.
v (transitive|computing) To introduce (code) into an existing program or its memory space, often without tight integration and sometimes through a security vulnerability.