umber n.

early 15c., "shadow, darkness, shade," from Old French ombrage "shade, shadow," from noun use of Latin umbraticum "of or pertaining to shade; being in retirement," neuter of umbraticus "of or pertaining to shade," from umbra "shade, shadow," from PIE root *andho- "blind; dark" (source also of Sanskrit andha-, Avestan anda- "blind, dark").

The English word had many figurative uses in 17c.; the one remaining, "suspicion that one has been slighted," is recorded by 1610s; hence phrase to take umbrage at, attested from 1670s. Perhaps the sense notion is similar to whatever inspired the modern (by 2013) slang verbal phrase throw shade "(subtly) insult (something or someone)."

brownish-ochre color, by 1760 (terra-sienna), from Italian terra di Sienna "earth of Siena," region in Italy where the coloring material first was produced from a type of earth mined there. It is used as a pigment in both oil and watercolor painting. See Siena.

Burnt sienna is the raw material roasted in a furnace before powdering. By this means the color is changed to a warm reddish brown similar to old mahogany. It is, like raw sienna, translucent in body. [Century Dictionary]