A
hedon is a unit of
pleasure used by utilitarians. A utilitarian will probably grant you that saying something like: "Eating
a really tasty sandwich gives me five hedons of pleasure, but having
sex with my
SO gives me five hundred hedons of pleasure." sounds completely arbitrary. They don't really want to imply that this is actually some kind of perfect objective measurement. What a utilitarian really wants to say here is that having sex is a hundred times more pleasurable than eating a sandwich.
Hedons are often used in conjunction with
dolors in examples of
hedonistic calculus. For example: "going to the dentist may cost me fifty dolors of pain now, but I will gain seventy hedons of pleasure from having healthy teeth and gums. I have a net of twenty hedons therefore I should go to the dentist."