the act of injecting or throwing in; -- applied particularly to the forcible throwing in of a liquid, or aeriform body, by means of a syringe, pump, etc.-that which is injected; especially, a liquid medicine thrown into a cavity of the body by a syringe or pipe; a clyster; an enema.-the act or process of filling vessels, cavities, or tissues with a fluid or other substance.-a specimen prepared by injection.-the act of throwing cold water into a condenser to produce a vacuum.-the cold water thrown into a condenser.