Entertaiment is a kind of activity that involves playing games, going to parties, watching performances, and taking part in other leisure activities.  It’s also something that children do a lot of, and it can be valuable for their development (for example, by teaching them social skills) and helping to prepare them for adult responsibilities or jobs, such as child rearing or sports (1,6).
You might abbreviate entertainment to entmt on a flier or in industry news publications where space is limited. However, this is not common outside of these contexts.
The power of entertainment is demonstrated by the way that stories can inspire a range of different forms – for example, composers such as Rimsky-Korsakov and Ravel have written orchestral works about Scheherazade, a character from Persian professional storytelling tradition; and directors such as Pasolini and Spielberg have made films of her story.