Home›Browse›P›placentalplacentalOur editors are putting together more complete content — check back in about 20 minutesplacentalplacental — adjectiveadjective1. relating to the placenta, the organ that feeds a developing baby in the womb1.adjectiveDefinitionrelating to the placenta, the organ that feeds a developing baby in the wombExamplePlacental mammals give birth to live young.