Aplasia

n. lack of development (of an organ or tissue)

Aplasia (Greek: a—not; plésein—to form) is defective development resulting in the absence of all or part of an organ.
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Aplasia /apla·sia/ lack of development of an organ or tissue.aplas´tic aplasia axia´lis extracortica´lis conge´nita familial centrolobar sclerosis. [more]Aplasia - Community and Resources

Noun
1. failure of some tissue or organ to develop
(hypernym) dysplasia

n. aplasia, lack of development