heterology

from The Century Dictionary.

• noun Abnormality; want or absence of homology or true morphological affinity; structural difference from a type or normal standard. Thus, cancer-cells exhibit heterology in comparison with healthy tissues.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Biol.) The absence of correspondence, or relation, in type of structure; lack of analogy between parts, owing to their being composed of different elements, or of like elements in different proportions; variation in structure from the normal form; -- opposed to homology.
• noun (Chem.) The connection or relation of bodies which have partial identity of composition, but different characteristics and properties; the relation existing between derivatives of the same substance, or of the analogous members of different series. Cf. Homology.

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

• noun A lack of correspondence between parts that reflect a difference in origin

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

• noun (biology) the lack of correspondence of apparently similar body parts