A pouch or sac without opening, usually membranous and containing morbid matter, which is accidentally developed in one of the natural cavities or in the substance of an organ.
A small capsule or sac of the kind in which many immature entozoans exist in the tissues of living animals; also, a similar form in Rotifera, etc.
A form assumed by Protozoa in which they become saclike and quiescent. It generally precedes the production of germs. See Encystment.