Webster’s Revised Unabridged Dictionary · 1913 Polycystidea Pol′y·cys·tid′e·a, n. pl. [NL. See Poly-, and Cystidea.] (Zoöl.) A division of Gregarinæ including those that have two or more internal divisions of the body. ‹ Polycystid Polycystina ›