Entertaiment is any form of cultural activity that a person consumes, for the purpose of eliciting pleasure or enjoyment. The word derives from the Latin intertenere, meaning to hold inside. It is also related to the Indo-European root ten, which means to stretch.
Entertainment often hits on the points that our brains were evolved to react deeply to, like social backstabbing or murders. It also stimulates the brain to realease seratonin and dopamine, which are feel good chemicals.
Oliver and Barstsch (2010) define entertainment as an objectively understood activity that communicates between text and audience, contains external stimulus, offers pleasure and requires the presence of an audience in a passive form.