To throw in; to dart in; to force in; as, to inject cold water into a condenser; to inject a medicinal liquid into a cavity of the body; to inject morphine with a hypodermic syringe.
- To force or drive (a fluid) into something: inject fuel into an engine cylinder; inject air into a liquid mixture.
- Medicine To introduce (a drug or vaccine, for example) into a body part, especially by means of a syringe.
- To treat by means of injection: injected the patient with digitalis.
- To introduce into conversation or consideration: tried to inject a note of humor into the negotiations.
- To place into an orbit, trajectory, or stream.