General synonyms:
* Amusement
* Diversion
* Recreation
* Pastime
* Fun
* Enjoyment
* Delight
* Stimulation
* Distraction
More specific synonyms:
* For movies, TV, etc.:
* Spectacle
* Show
* Performance
* Production
* For music:
* Concert
* Performance
* Entertainment
* For theater:
* Play
* Show
* Drama
* Performance
The best synonym for "entertainment" depends on the specific context and what you want to emphasize.