n.

1. 循環，環流；運行[U][S1]
   We observed the circulation of blood in frogs.

   我們觀察了青蛙的血液循環。

2. （貨幣、消息等的）流通，傳播[U]
   Many forged notes are in circulation.

   許多假鈔在流通。

3. （報刊等的）發行量，銷售量[S]
   This paper has a circulation of more than a million.

   這一報紙的發行量達一百多萬份。

4. 通貨，貨幣[U]

n.

1. movement to and fro or around something.
   ▸the continuous motion by which blood travels through the body.
2. the public availability or knowledge of something:
   his music has achieved wide circulation.
3. the number of copies sold of a newspaper or magazine.