n.

1. 丧失；遗失[U]
   He suffered a temporary loss of memory.

   他暂时丧失了记忆。

2. 损失；亏损（额）[C][U]
   It is a great loss to her.

   这是她的巨大损失。

   His death means a great loss to science.

   他的死是科学的重大损失。

3. 输，失败[U][C]
   The loss of the first game did not discourage them.

   第一场比赛的失败并没有令他们沮丧。

4. 减少，减低[S1]
   When heavy atoms are split in this way some loss of mass occurs.

   当重原子这样被分裂的时候，就会发生质量的减少。

n.

1. the fact or process of losing something or someone.
   ▸the feeling of grief after losing a valued person or thing.
   ▸a person or thing that is badly missed when lost.
2. a defeat in sport.
3. the amount by which money spent in operation or production exceeds money earned.