Quiz: Remember the definition of mal de mer?
early 15c., "deep red color," from Old Spanish cremesin "of or belonging to the kermes" (the shield-louse insects from which a deep red dye was obtained), from Medieval Latin cremesinus (see kermes). For similar transfer of the dye word to generic use for "red," cf. Old Church Slavonic čruminu, Russian čermnyj "red," from the same source.
c.1600, from crimson (n.). Related: Crimsoned; crimsoning.