Bones

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. 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. 

In the alternate reality, refers to  as bones because, as according to the doctor the first time they met, that's all his ex-wife left him after his divorce.