What is the X in X-mas?
viviparous vi·vip·a·rous (vī-vĭp'ər-əs, vĭ-)
Giving birth to living offspring that develop within the mother's body as for most mammals.
Giving birth to living young that develop within the mother's body rather than hatching from eggs. All mammals except the monotremes are viviparous. Compare oviparous, ovoviviparous.