1. enter- (inter-) + -tain + -ment.
2. => keep or hold someone's mind among many different and interesting things.
=> keep or hold something like amusing or treat between / among people.
=> keep or hold something attractive or interesting among / in one's mind.
3. 所谓花花世界、五彩缤纷、其乐无穷，由此引申义：娱乐，助兴。
4. 类推：The original Old French version of enterprise was emprise.
5. => The original Old French version of entertain was *emtenir(*emtain).
6. 因此这里的enter-前缀应该说还含有“in”的含义，这还可以从单词enter及该前缀的源头可以看出来。
7. enter- "in" => hold or keep one's mind in something, hold (in), keep (in), maintain (in).

1. Crudeness is on the rise in all fields of entertainment.

所有娱乐领域都日益粗俗化。

2. One day virtual reality will revolutionize the entertainment industry.

有一天虚拟现实将使娱乐业发生革命性的变化。

3. You'll need to provide continuous, organised entertainment or children may get over-excited.

你要提供连贯有序的娱乐活动，否则孩子们就有可能兴奋过头。

4. Gambling is a form of entertainment.

赌博是一种娱乐。

5. There's something charminglyold-fashioned about his brand of entertainment.

他自成一格的表演有一种迷人的旧情调。