medical specialist vs gerontologist

Other hyponyms of medical specialist include anaesthetist, anesthesiologist, anesthetist, baby doctor, paediatrician, pediatrician, pediatrist, cardiologist, heart specialist, heart surgeon, chiropodist, foot doctor, podiatrist, dermatologist, skin doctor, diagnostician, pathologist, diplomate, ear doctor, ear specialist, otologist, embryologist, endocrinologist, ear-nose-and-throat doctor, ENT man, otolaryngologist, otorhinolaryngologist, rhinolaryngologist, geriatrician, gynaecologist, gynecologist, woman's doctor, haematologist, hematologist, hygienist, internist, brain doctor, neurologist, accoucheur, obstetrician, oncologist, eye doctor, oculist, ophthalmologist, orthopaedist, orthopedist, orthoptist, proctologist, head-shrinker, psychiatrist, shrink, radiographer, radiologist, radiotherapist, rheumatologist, urologist.