13 letters · 24 points in Scrabble
adjective of or relating to monochromatism
adjective (of light or other electromagnetic radiation) having only one wavelength
adjective having or appearing to have only one color
originFrom mono- + chromatic, mono- from Ancient Greek μόνος (mónos, “alone, only, sole, single”), chromatic from Ancient Greek χρῶμα (khrôma, “color”).
Etymology from Wiktionary, CC BY-SA 3.0