color

Color, coloris is a third declension masculine. Older texts spell the nominative colos, which explains the r everywhere else: the stem was colos-, and an s between two vowels turned into an r in early Latin. Honor, honoris and arbor, arboris did the same thing.

Beyond pigment it covers complexion - colorem mutare is to go pale or flush - and the general look of a thing. Rhetoricians use it for the gloss put on an awkward case, which is exactly the modern sense of "putting a colour on it". The word is usually connected with celo, "to conceal", colour being what covers a surface. British English keeps the u from French colour; the Latin has none, so do not let the spelling drift when you write coloris.