Stimuli that can cause pain are referred to as C. noxious.
These types of stimuli can cause little to a lot pain, and can be mechanical (such as pinching), thermal (when the temperature is high or low), and chemical (if you are exposed to an acid, for example).
Innocuous stimuli do not cause pain. Painful and harmful stimluli is not a term used in biology, but rather noxious stimuli.
