Longman Dictionary of Contemporary English
Wiktionary
n. A hospital in which trainee doctors obtain practical training and experience.
Wikipedia
A teaching hospital is a hospital or medical center that provides clinical education and training to future and current health professionals. Teaching hospitals are often affiliated with medical schools and work closely with medical students throughout their period of matriculation, and especially during their clerkship (internship) years. In most cases, teaching hospitals also offer Graduate Medical Education (GME)/ physician residency programs, where medical school graduates train under a supervising (attending) physician to assist with the coordination of care.
In addition to offering medical education to medical students and physician residents, many teaching hospitals also serve as research institutes.