Definition of shin:
(n) :
the front part of the leg below the knee; the front edge of the shin bone; the lower part of the leg; the shank; the twenty first letter of the
Hebrew alphabet,
?
(v) :
to climb a mast, tree, rope, or the like, by embracing it alternately with the arms and legs, without help of steps, spurs, or the like; -- used with up
"to shin up a mast"