chorionPronunciation: /ˈkɔːrɪən/Definition of chorion noun Embryology the outermost membrane surrounding an embryo of a reptile, bird, or mammal. In mammals it contributes to the formation of the placenta. Derivatives chorionicPronunciation: /ˌkɒrɪˈɒnɪk/ adjective Origin: mid 16th century: from Greek khorionchorion in other Oxford dictionaries Definition of chorion in the US English dictionary
