AT: "xx" Template:Disambiguate Bones was a nickname for Doctor Leonard McCoy in multiple realities.
In the prime reality, Bones is short for "Saw Bones"; the term was used by James T. Kirk almost exclusively to refer to Leonard McCoy during their service together. (TOS: "The Man Trap", "A Piece of the Action"; Star Trek VI: The Undiscovered Country) During a 2267 away mission on Pyris VII, Kirk made a special point to avoid calling McCoy "Bones", instead using the nickname "Doc", after finding themselves in shackles hanging alongside a skeleton. (TOS: "Catspaw")
In the alternate reality, James T. Kirk refers to Leonard McCoy as bones because, as according to the doctor the first time they met, that's all his ex-wife left him after his divorce. (Star Trek)