cacogenesis

from The Century Dictionary.

• noun In medicine, a morbid formation, whether congenital, as a monstrosity, or of later development, as a tumor.
• noun The quality, common in mixed breeds, of having a low vitality and of being infertile.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun medicine A morbid, monstrous, or pathological growth or product; an abnormality in structure; a monstrosity.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun inability to produce hybrids that are both viable and fertile