(ˌ)āˈjenəsə̇s noun
( plural agene·ses -əˌsēz)
Etymology: New Latin, from a- (II) + genesis
1. biology : lack of development : faulty or incomplete development
cerebral agenesis
2. also age·ne·sia |ājəˈnēzh(ē)ə -s medicine : the complete absence of an organ or part due to the absence of or a defect in its embryologic anlage — compare aplasia