WordNet (r) 3.0 (2006):

internist
    n 1: a specialist in internal medicine

Moby Thesaurus II by Grady Ward, 1.0:

26 Moby Thesaurus words for "internist":
   anesthesiologist, cardiologist, chiropodist, dermatologist,
   eye doctor, eye-ear-nose-throat specialist, geriatrician,
   gerontologist, gynecologist, immunologist, neurologist,
   obstetrician, oculist, ophthalmologist, orthopedist,
   otolaryngologist, otologist, pathologist, pediatrician, pediatrist,
   podiatrist, psychiatrist, radiologist, serologist, skin man,
   specialist