Aplasia (from Greeka—not; plasis—molding) is defined in general as "defective development or congenital absence of an organ or tissue." In the field of hematology, the term refers to "incomplete, retarded, or defective development, or cessation of the usual regenerative process."
The Collaborative International Dictionary
Aplasia \A*pla"si*a\, n. [NL.; Gr. ? priv. + ? a molding.] (Med.)
Incomplete or faulty development.
(Med.) a defect, retardation, or cessation of the process of generation of blood cells.
n. (context pathology English) A condition marked by the incomplete development, or absence, of an organ or tissue.
Douglas Harper's Etymology Dictionary
1885, medical Latin, from Greek a-, privative prefix (see a- (3)), + -plasia.
n. failure of some tissue or organ to develop
Usage examples of "aplasia".
Patrick had granted Caitlin permission to speak with Stephen, to learn the details of his aplasia down to the electron micrographs of his barren marrow.