Much of the contention and confusion that inevitably arise whenever the subject of pain in animals stems from problems with the word "pain" itself. When used to describe responses in humans,
"pain" can mean any subset of a vast spectrum of sensations and emotions, ranging from the instantaneous, galvanizing effect of a dentist drill hitting the nerve in a molar to more airy notions such as the "pain" of rejection or "painfully" embarrassing situations. Humans even use concepts as abstruse as the German term weltschmerz, or "world pain," which denotes a vaguely defined depression or despair.
Murphy, Dana H.
"The Problem of Pain: What Do Animals Really Feel?,"
International Journal for the Study of Animal Problems: Vol. 3:
4, Article 8.
Available at: https://www.wellbeingintlstudiesrepository.org/ijsap/vol3/iss4/8