(anatomy) A (non-gestational) sac that develops in the uterus during an ectopic pregnancy

plural of pseudosac

(organic chemistry) Any of several heterocyclic compounds that have a five-membered ring with two oxygen atoms in positions 1- and 3-.

Apparently, but not actually, sacred.

plural of pseudosacrifice

Something resembling a sacrifice that is not a true sacrifice, especially (chess) an offer of material made at no risk, since acceptance would lead to the gain of equal or greater material or checkmate.