Hoss is a professional wrestling term. It is slang for a professional wrestler with little talent and poor workrate, and often not much charisma. Hosses are disliked by the smark community. They are hired mainly for their size. Some model hosses are Heidenreich, Viscera, and Gene Snitsky.
The term "Hoss" was coined by Jim Ross. Its cultural origin lies with "Hoss" Cartwright of the TV series Bonanza. Ross uses it as a positive term, using it to say that a wrestler is large, powerful, and unstoppable (in kayfabe). However, since many of the wrestlers he applies it to are significantly lacking in the talent and/or charisma departments, and rely exclusively on their size to get over, it has come to assume its current meaning as an insult among wrestling fans.