1. anatomy organ in uterus of pregnant mammal: a vascular organ that develops inside the uterus of most pregnant mammals to supply food and oxygen to the fetus through the umbilical cord. It is expelled after birth.
2. botany part of ovary of plant: the part of the ovary in a flowering plant that bears ovules
3. botany spore-bearing mass of tissue: the tissue in a nonflowering plant where the sporangia or spores develop
