n. underdevelopment or incomplete development of a tissue or organ, especially when caused by an inadequate or below-normal number of cells
The Century Dictionary and Cyclopedia
n. Deficient growth or atrophy of a part through excessive destruction or defective formation of cells.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. underdevelopment of an organ because of a decrease in the number of cells
Word Usage
"If she falls over when blindfolded (because she relies on her eyes for balance), she probably has cerebellar hypoplasia, which is more common in kittens."