English word ectoplacental comes from English placental, English ecto- (Outside.)

Detailed word origin of ectoplacental

Dictionary entry	Language	Definition
placental	English (eng)	Having a placenta.. Of or pertaining to the placenta, or to the Placentalia Any animal that is a member of the Placentalia.
ecto-	English (eng)	Outside.
ectoplacental	English (eng)	(anatomy) Outside, or surrounding the placenta.

Words with the same origin as ectoplacental