Lithol

noun

Lith·​ol

variants or less commonly lithol

ˈliˌthȯl,

-ōl

: any of a group of organic pigments most of which consist essentially of salts of difficultly soluble azo compounds

In painting the Harvard murals, Rothko used an organic pigment called Lithol red that is readily destroyed by light.

—Edward J. Sozanski, Chicago Tribune, 22 Sept. 1988

—formerly a U.S. registered trademark

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