n.

1. 应用，适用；运用[U][C][（+of/to）]
   Biology has practical applications.

   生物学有实用性。

2. 申请，请求；申请书[C][U][（+to/for）][+to-v]
   I made an application for a loan.

   我申请一笔贷款。

3. 施用，敷用搽剂[U][C]
   The application of varnish made the desk shine.

   上了清漆桌子发亮了。

4. 用功，专心[U][（+to）]
   application to one's work

   专心工作

n.

1. a formal request to an authority.
2. the action of putting something into operation.
   ▸practical use or relevance.
3. the action of applying something to a surface.
4. sustained effort.
5. Computing  a program or piece of software designed to fulfil a particular purpose.