The suffix "-ism" refers to which of the following?

The suffix "-ism" denotes a state of being, condition, or theory. It is commonly used in medical terminology as well as in other fields to describe a particular philosophical or ideological doctrine, or a pathological condition. For example, "hypothyroidism" refers to a state of having an underactive thyroid, which exemplifies how the suffix indicates a condition related to the thyroid's function. This understanding of "-ism" as indicating a specific state or condition is what makes it the correct choice in the context of this question.

Other suffixes mentioned in the options have distinct meanings: "action" is often represented by "-tion" or "-sion," "pertaining to" is typically conveyed by "-al" or "-ic," while "specialist" is marked by the suffix "-ist." These distinctions clarify why "-ism" specifically connects to a condition or state, reinforcing its specific use in medical terminology.