ochre (n.)

common name of a type of clayey soil much used in pigments, late 13c., oker, ocre, from Old French ocre (c. 1300) and directly from Medieval Latin ocra, from Latin ochra, from Greek khra, from khros "pale yellow," a word of unknown origin. It consists hydrated sesquioxids of iron mixed with various earthy materials, principally silica and alumina. As a color name, "brownish-yellow," it is attested from mid-15c. Related: Ochreous.