Pain is discomfort or hurt.
It is often described in terms of a penetrating or tissue-destructive process (e.g., stabbing, burning, twisting, tearing, squeezing) and/or of a bodily or emotional reaction (e.g., terrifying, nauseating, sickening).
Furthermore, any pain of moderate or higher intensity is accompanied by anxiety and the urge to escape or terminate the feeling.
These properties illustrate the duality of pain: it is both sensation and emotion.
When it is acute, pain is characteristically associated with behavioral arousal and a stress response consisting of increased blood pressure, heart rate, pupil diameter, and plasma cortisol levels. 1