Merriam-Webster Online: taxi·der·my: noun. 1820. The art of preparing, stuffing, and mounting the skins of animals and especially vertebrates.
Wikipedia: Taxidermy (Greek for "the arrangement of the skin") is the art of mounting or reproducing animals for display (e.g. as hunting trophies) or for study. Taxidermy can be done on all species of animals. The methods that taxidermists practice have been improved over the last century, heightening taxidermic quality.
Taxidermists may practice professionally, for museums or as a business catering to hunters and fishermen, or as amateurs, such as hobbyists, hunters, and fishermen. To practice taxidermy, one must be extremely familiar with anatomy, dissection, sculpture, and painting, as well as tanning.
Encyclopædia Britannica: Practice of creating lifelike representations of animals by using their prepared skins and various supporting structures.
Taxidermy began with the ancient custom of keeping trophies of the hunt. Beginning in the 18th century, a growing interest in natural history resulted in collections and exhibits of birds, beasts, and curiosities. Chemically preserving skins, hair, and feathers made it possible to recreate the appearance of live animals by stuffing the sewed-up skin with straw or hay. Constructing and sculpting anatomically correct manikins of clay and plaster are the basis of modern taxidermy.