acephalocyst

Acephalocyst \A*ceph"a*lo*cyst\, n. [Gr. 'ake`falos without a head + ky`stis bladder.] (Zool.) A larval entozo["o]n in the form of a subglobular or oval vesicle, or hydatid, filled with fluid, sometimes found in the tissues of man and the lower animals; -- so called from the absence of a head or visible organs on the vesicle. These cysts are the immature stages of certain tapeworms. Also applied to similar cysts of different origin. [1913 Webster]