"Hospitalist" is actually a real clinical position.

It's relatively new (only really being created in the last two decades) and is more of a role/job than a specialty itself, as people work as "hospitalists" but there's no formal training to become one.

Hospitalists are mostly Internal Medicine and Family Medicine physicians who solely take care of patients admitted to hospital as the "Most Responsible Physician" even though other surgeons and specialists may still consult and be involved.

Essentially, hospitalists do all the grunt work for admitted patients - take care of the nuisance requests from patients and nurses for pain meds and sleeping pills, round on patients daily, plan discharges, coordinate with the physiotherapist/dietitian/occupational therapist/social worker, etc.

Essentially the position was created because

1. patients used to be admitted to hospital under their family doctor traditionally, but the demands of outpatient clinics and the increasing complexity of hospital stays essentially made this extinct

2. specialists don't want to be bothered with the day-to-day mundane care of patients admitted to their service on the wards. Surgeons want to be in the Operating Room cutting instead of following up on the patients they already cut. Specialists want to assess new consults rather than catering to old ones. Hospitals want their profitable surgeons and specialists to be producing new widgets, not babying old ones.