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
see also:
tawny tan bark tan bed tan pickle tan spud tan stove 
bark stove bark tan vat