Which suffix relates to "pain"?

The suffix that specifically relates to "pain" is -algia. This suffix is derived from Greek, where "algos" means pain. In medical terminology, -algia is used to describe conditions characterized by pain in a specific area of the body. For example, "neuralgia" refers to pain along the nerves, and "myalgia" refers to muscle pain.

On the other hand, -itis refers to inflammation, which may or may not involve pain as a symptom. -oma indicates a tumor or a mass, often benign or malignant, and does not denote pain. -pathy is used to describe diseases or disorders, but it does not specifically refer to pain. Thus, -algia is the most accurate suffix to indicate pain in medical terms.