It's often used in medical terms to indicate someone who specializes in a particular field of medicine.
Here are some examples:
* Pediatrician: A physician specializing in the care of children.
* Geriatrician: A physician specializing in the care of elderly people.
* Psychiatrist: A physician specializing in the diagnosis, treatment, and prevention of mental disorders.
* Ophthalmologist: A physician specializing in the diagnosis and treatment of eye disorders.
* Podiatrist: A physician specializing in the care of feet.
Note: While "-iatr" is a common suffix in medical terminology, it's not always used. Some medical specialties use different suffixes, such as "-ologist" or "-ist".