Holy shit! English has an actual name to that elusive color that in Brazilian Portuguese we infomally call "cor-de-burro-quando-foge" (literally "the color of a donkey as he runs away" -- yes, I'm not making this up).

TAUPE (pron. "tope", rhymes with "hope")

From Wikipedia: "Taupe is a vague color term which may refer to almost any grayish brown or brownish gray, but true taupe is difficult to pinpoint as brown or gray."

AND this name is also derived from an animal! (it's French for "mole").