Entertainment is an agreeable occupation of the mind, a diversion, or amusement. It may be as simple as solving a crossword puzzle or as complex as an opera or a theatrical performance. Some forms of entertainment have a serious purpose, such as ceremony or religious festival, while others may serve a social function such as public execution or satire. Entertainment has also proven to be highly adaptable, with activities that were once a part of work or military training now being performed for the enjoyment of spectators.
You may abbreviate the word entertain to entmt on a flier or in industry news publications, but only in a limited context where space is at a premium. It is not generally used in general writing.