What is the X in X-mas?
Old English scinu "shin, fore part of the lower leg," from Proto-Germanic *skino "thin piece" (cf. Dutch scheen, Old High German scina, German Schienbein "shin, shinbones"), from PIE root *skei- "to cut, split" (see shed (v.)). Shin splints is attested from 1930.
"to climb by using arms and legs" (originally a nautical word), 1829, from shin (n.). Related: Shinned; shinning.
The front part of the leg located below the knee and above the ankle.