n.

1. （现只用于at random）任意行动；随机过程[U]
   He took a book at random.

   他随手取了一本书。

a.

1. 胡乱的；随便的，任意的
   He was not listening and made a random answer to the teacher's question.

   他不在听讲，对教师的问题瞎答一通。

2. （建筑材料等）大小不一的，规格不一的
3. 【统】随机的
   random sampling

   随机取样

4. 【物】无规则的

adj.

1. made, done, or happening without method or conscious decision.
   ▸Brit. informal rather strange; odd.
2. Statistics  governed by or involving equal chances for each item.
3. (of masonry) with stones of irregular size and shape.