From WordNet (r) 3.0 (2006) [wn]:
tanned
adj 1: (of skin) having a tan color from exposure to the sun; "a
young bronzed Apollo" [syn: bronzed, suntanned,
tanned]
2: converted to leather by a tanning agent [ant: untanned]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Tan \Tan\, v. t. [imp. & p. p. Tanned; p. pr. & vb. n.
Tanning.] [F. tanner, LL. tannare. See Tan, n.]
1. To convert (the skin of an animal) into leather, as by
usual process of steeping it in an infusion of oak or some
other bark, whereby it is impregnated with tannin, or
tannic acid (which exists in several species of bark), and
is thus rendered firm, durable, and in some degree
impervious to water.
[1913 Webster]
Note: The essential result in tanning is due to the fact that
the tannins form, with gelatins and albuminoids, a
series of insoluble compounds which constitute leather.
Similar results may be produced by the use of other
reagents in place of tannin, as alum, and some acids or
chlorides, which are employed in certain processes of
tanning.
[1913 Webster]
2. To make brown; to imbrown, as by exposure to the rays of
the sun; as, to tan the skin.
[1913 Webster]
3. To thrash or beat; to flog; to switch; as, to tan a
disobedient child's hide. [Colloq.]
[Webster 1913 Suppl. +PJC]