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1. The act of passing.
2. A discharge, as from the bowels or of urine.
3. Inoculation of a series of animals with the same strain of a pathogenic microorganism whereby the virulence usually is increased, but is sometimes diminished.
4. A channel, duct, pore, or opening.
[Mediev. L. passo, to pass]
a. A path, channel, or duct through, over, or along which something may pass: the nasal passages.
b. A corridor.
2. Physiology The process of discharging something from a bodily part, such as evacuation of waste from the bowels.
3. Medicine The introduction of an instrument into a bodily cavity.
1 an opening, channel, route, or gap.
2 the movement of something from one place to another, as in evacuation of the bowels.
introduction followed by recovery of an infectious agent in an experimental animal or culture medium.
passage of an infectious agent through an experimental animal or medium without there being any evidence, clinical or cultural, that the agent is present.
repeated passage through a series of experimental animals or media, often with the objective of altering the virulence of the agent or adapting it to grow better.