metamerism

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The condition of having the body divided into metameres, exhibited in most animals only in the early embryonic stages of development.

Century Dictionary and Cyclopedia

1. n. In chem., a form of isomerism, that property of certain compound bodies by which they have the same chemical elements combined in the same proportion and with the same molecular weight, while differingin chemical properties. Thus, aldehyde and ethylene oxid have their elements in the same proportion, C₂H₄O, and the same molecular weight, 44, but are very different in their chemical properties. Two metameric bodies do not, however, belong to the same class or series of compounds. See isomerism, polymerism.
2. n. In zoology, a metameric condition; the state of being metameric; segmentation of the body of an animal along the primary or longitudinal axis, resulting in a series of more or less similar consecutive parts which are serially homologous. See metamere, antimere.

Wiktionary

1. n. biology The segmentation of the body into similar discrete units
2. n. colorimetry The matching of apparent color of objects with different spectral power distributions.
3. n. chemistry structural isomerism

GNU Webster's 1913

1. n. (Biol.) The symmetry of a metameric structure; serial symmetry; the state of being made up of metameres.
2. n. (Chem.) The state or quality of being metameric; isomerism due to different bonding patterns in two substances having the same molecular formula. Contrasted with steroisomerism or optical isomerism. Also, the relation or condition of metameric compounds.