A person or thing that entertains.

Dan has a lot of stereo entertainment equipment in his room.
A person whose work is to amuse people at a show is an entertainer.
I enjoy watching movies for entertainment.
A restaurant that serves food and provides entertainment to their customers is a fun place to go.
From Middle English entertaiment, from Old French entretenement (“support, maintenance”), from entre- “among” (from Latin inter) + tenir “to hold” (from p. root *tenere ‘to stretch, extend’). The sense of “gratify, amuse” is late 15c. The suffix -ment is common in English forming nouns from verb stems, as in amazement, betterment, and merriment. It replaced the earlier -mentum, which was formed from Latin -mentum, with some verbs in which -i- usually occurs between the stem and -ment (as in sentir). More at entry.