color index

noun

, Astronomy.

1. the difference between the apparent photographic magnitude and the apparent visual magnitude of a star.
2. the difference between the magnitudes of a star in any two spectral regions.

Word History and Origins

Origin of color index¹

First recorded in 1920–25

Example Sentences

A low color-index probably indicates a mild type of the disease.

From Project Gutenberg

The color-index is thus almost invariably low, the average being about 0.5.

From Project Gutenberg

The changes in hemoglobin and red cells resemble those of a moderate symptomatic anemia, with rather low color-index.

From Project Gutenberg

The color index is most significant in chlorosis and pernicious anemia.

From Project Gutenberg