Which suffix is used to denote a specialist in a particular field?

The suffix that denotes a specialist in a particular field is -ician. This suffix is derived from Latin and is commonly used in medical and scientific terminology to indicate a person who has expertise or specialization in a certain area. For example, terms like physician, technician, and practitioner all use the suffix -ician to indicate that the person has a specialized knowledge or skill set relevant to their field of practice.

The other options do not serve the same function. The suffix -ism refers to a distinctive practice, system, or philosophy, such as in the word socialism, which denotes a particular ideology rather than a specialist. The suffix -ile is used to denote capability or susceptibility, as in volatile, which describes characteristics but does not imply specialization. Lastly, -istry is typically used to refer to a field of study or practice, such as in chemistry or pastry, but it does not specify a specialized individual. Therefore, the suffix -ician is the most accurate choice to convey specialization in a given domain.