dorsum

noun

1
the back of the body of a vertebrate or any analogous surface (as the upper or outer surface of an organ or appendage or part)
the dorsum of the foot
2
the posterior part of a human (or animal) body from the neck to the end of the spine
his back was nicely tanned

Also useful for “dorsum”:Unscrambler— Rearrange the letters in “dorsum”