The Collaborative International Dictionary of English v.0.48:
Tan \Tan\, n. [F. tan, perhaps fr. Armor. tann an oak, oak bar;
or of Teutonic origin; cf. G. tanne a fir, OHG. tanna a fir,
oak, MHG. tan a forest. Cf. Tawny.]
1. The bark of the oak, and some other trees, bruised and
broken by a mill, for tanning hides; -- so called both
before and after it has been used. Called also tan bark.
[1913 Webster]
2. A yellowish-brown color, like that of tan.
[1913 Webster]
3. A brown color imparted to the skin by exposure to the sun;
as, hands covered with tan.
[1913 Webster]
Tan bed (Hort.), a bed made of tan; a bark bed.
Tan pickle, the liquor used in tanning leather.
Tan spud, a spud used in stripping bark for tan from trees.
Tan stove. See Bark stove, under Bark.
Tan vat, a vat in which hides are steeped in liquor with
tan.
[1913 Webster]