a.

1. 圓的，圓形的；環形的；環行的[Z]
   The full moon has a circular shape.

   滿月呈圓形。

2. 循環的[Z]
3. 迂迴的，拐彎抹角的，不直截了當的
   I'm not satisfied with his circular explanation.

   我不滿意他拐彎抹角的解釋。

4. 供流傳的，供傳閱的[Z]

n.

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

   該組織每月發一份通告。

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.