Entertaiment can be a great source of fun and enjoyment. But sometimes it can be very disturbing. The reason is because entertainment often hits on the themes that are very close to how the human brain was shaped to react deeply to. Such as backstabbing, murders and other aspects of the social world. It is also well known that the mind reacts very deeply to entertainment because it stimulates the production of seratonin and dopamine.
You might see the word entertainment abbreviated to entmt on a flier or in industry news publications, where space is limited. But it is very uncommon to see it abbreviated in general use.