sable (n.1)

"fur or pelt of the European sable" (Martes zibellina), early 15c., from Old French sable (also martre sable "sable martin"), in reference to the mammal or its fur, borrowed in French from Germanic (Middle Dutch sabel, Middle Low German sabel, Middle High German zobel), ultimately from a Slavic source (compare Russian, Czech sobol, Polish soból, the name of the animal), "which itself is borrowed from an East-Asiatic language" [Klein], but Russian sources (such as Vasmer) find none of the proposed candidates satisfactory.

sable (n.2)

"black" as a heraldic color, early 14c., commonly identified with sable (n.1), but the animal's fur is brown and this may be a different word of unknown origin; or it might reflect a medieval custom (unattested) of dyeing sable fur black. As an adjective from late 14c. Emblematic of mourning or grief from c. 1600; c. 1800 as "black" with reference to Africans and their descendants, often with mock dignity.

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Definitions of sable from WordNet
sable (n.)
an artist's brush made of sable hairs;
Synonyms: sable brush / sable's hair pencil
sable (n.)
the expensive dark brown fur of the marten;
sable (n.)
a very dark black;
Synonyms: coal black / ebony / jet black / pitch black / soot black
sable (n.)
a scarf (or trimming) made of sable;
sable (n.)
marten of northern Asian forests having luxuriant dark brown fur;
Synonyms: Martes zibellina
sable (adj.)
of a dark somewhat brownish black;