Entertaiment is an interesting word, and it has a very wide range of meanings. You may see it abbreviated to entmt on a flier or in some industry news publications, where space is limited. However, it is not common to abbreviate this word in normal writing.
Entertainment is an activity or event intended to amuse, titillate, or stimulate the audience. It can take many forms and be adapted to different levels of complexity, from a simple game or performance for a single person to global competitions and spectator sports that attract millions of viewers. Many familiar forms of entertainment have persisted across the centuries and diversified with new technology, for example: stage magic and films that tell stories, drama, or play music.