\Het`er*ol"o*gy\, n. [Hetero- + -logy.]
1. (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. (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; as, ethane, ethyl
   alcohol, acetic aldehyde, and acetic acid are in
   heterology with each other, though each in at the same
   time a member of a distinct homologous series. Cf.
   {Homology}.