bonus
/ˈbəʊnəs/noun
1- a payment or gift added to what is usual or expected, in particular额外给予的报酬（或礼物）, 尤指：
1.1
- an amount of money added to a person's wages, especially as a reward for good performance奖金：
big Christmas bonuses.
大笔的圣诞节奖金。
1.2
- Brit. an extra dividend or issue paid to the shareholders of a company〈英〉红利。
1.3
- Brit. a distribution of profits to holders of an insurance policy〈英〉（分给参加保险者的）余利。
1.4
- a welcome and often unexpected circumstance, action, or service that accompanies and enhances something that is itself good（附带的）好处, 优点：
good weather is an added bonus but the real appeal is the landscape.
晴朗的天气是额外的好事, 但真正吸引人的还是此处的风景。
词源
late 18th cent. (probably originally Stock Exchange slang)： from Latin bonus (masculine) 'good', used in place of bonum (neuter) 'good, good thing'.