Which suffix would be used for a specialist in a certain field?

The suffix that indicates a specialist in a certain field is "-iatrist." This suffix is commonly used in medical terminology to refer to practitioners in various healthcare specialties, such as a psychiatrist (a specialist in mental health) or a podiatrist (a specialist in foot and ankle care). The term denotes someone who has extensive training and expertise in a particular area of medicine.

The other suffixes have different meanings: "-logy" refers to the study of a specific subject (such as biology, the study of life), "-pathy" denotes a disease or disorder (like neuropathy, indicating a condition affecting nerves), and "-plasty" signifies surgical repair (such as rhinoplasty, which involves the surgical reshaping of the nose). Thus, while these suffixes are relevant in medical contexts, they do not indicate specialization in the way that "-iatrist" does.