- placenta
- 1677, from Mod.L. placenta uterina "uterine cake" (so called 16c. by It. anatomist Realdo Colombo), from L. placenta "flat cake," from Gk. plakoenta, accusative of plakoeis "flat," related to plax "anything flat," from PIE *plak-, extended form of base *pele- (see plane (n.)). So called from the shape.