a.

1. 圆的，圆形的；环形的；环行的[Z]
   The full moon has a circular shape.

   满月呈圆形。

2. 循环的[Z]
3. 迂回的，拐弯抹角的，不直截了当的
   I'm not satisfied with his circular explanation.

   我不满意他拐弯抹角的解释。

4. 供流传的，供传阅的[Z]

n.

1. 通知，公告；传单[C]
   The organization issues a circular every month.

   该组织每月发一份通告。

adj.

1. having the form of a circle.
2. Logic  (of an argument) already containing an assumption of what is to be proved.
3. (of a letter or advertisement) for distribution to a large number of people.

n.