the perception of physiological pain, usually evoked by stimuli that cause or threaten to cause tissue damage. In some cases, such as phantom limb pain and causalgia, the persistence of pain cannot be explained by stimulation of neural pathways. Pain perception can be measured in terms of its intensity and can be classified according to several categories: These include sharp or dull, focal or general, and chronic or intermittent or transitory. Also called nociception.