n.

1. 恩惠
   Your donation to the hospital was really a boon to those poor patients.

   你給醫院的捐贈對於那些貧窮的病人來說是真正的恩惠。

2. 利益
   Many people think that the new Disney World is a great boon to the fortunes of Shanghai.

   許多人認為，迪斯耐樂園是上海財政的一大利益。

a.

1. 快活的，歡樂的，令人愉悅的
2. 慷慨的

n.

1. a thing that is helpful or beneficial.
2. archaic a favour or request.