metamerism

noun

me·​tam·​er·​ism mə-ˈta-mə-ˌri-zəm 

1

: the condition of having or the stage of evolutionary development characterized by a body made up of metameres

The basic principle of arthropod design is metamerism, the construction of the body from an extended series of repeated segments.

—Stephen Jay Gould

2

: the identical visual appearance of two colors that have different physical or spectral compositions : the condition of being metameric in color

… the colors of dyes or pigments that match in daylight may not match in incandescent or fluorescent light, and so on, a characteristic known as metamerism.

—Kurt Nassau

Word History

Etymology

(sense 1) metamere or metamer(ic) + -ism, probably after German Metamerie or Metamerismus; (sense 2) metamer "either of two colors that appear identical to the eye but have different spectral composition" (probably back-formation from metameric) or metamer(ic) + -ism, after German Metamerie

First Known Use

1877, in the meaning defined at sense 1

Medical Definition

metamerism

noun

me·​tam·​er·​ism mə-ˈtam-ə-ˌriz-əm 

1

: isomerism especially of chemical compounds of the same type

2

: the condition of having or the stage of evolutionary development characterized by a body made up of metamers that is usually held to be an essential prelude to the differentiation of the more highly organized animals (as arthropods and vertebrates) through the disproportionate development and elaboration of some segments together with the coalescence, reduction, or loss of others

3

: the phenomenon exhibited by pairs of color metamers

the problem of metamerism in matching artificial with natural teeth