heterology

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Lack of correspondence between bodily parts, as in structure, arrangement, or development, arising from differences in origin.

Century Dictionary and Cyclopedia

1. n. 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.

Wiktionary

1. n. A lack of correspondence between parts that reflect a difference in origin

GNU Webster's 1913

1. n. (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.
2. n. (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.

WordNet 3.0

1. n. (biology) the lack of correspondence of apparently similar body parts