Something that affords pleasure, diversion, or amusement. For example, the daily crossword puzzle is an entertainment for many people. Similarly, a play or ballet is an entertainment. It is possible to abbreviate entertainment to entmt on a flier or in industry news publications where space is limited, but it is not generally used in general prose.
Some entertainers are able to take us to a different world where we forget our problems and wish that the moment could last forever. This is because entertainment hits on the things that the human brain was shaped to react deeply to, such as backstabbing, murders and other themes that we were shaped to understand in order to survive in the social world.