n.
Pronunciation: ˌ pla-s ə n- ' t ā -sh ə n, pl ə - ˌ sen-
Function: noun
Date: 1760
1 : the arrangement of placentas and ovules in a plant ovary
2 a : the development of the placenta and attachment of the fetus to the uterus during pregnancy b : the morphological type of a placenta