[ U ] the process in which something such as information, money, or goods passes from one person to another（信息）流传，传播；（货币或商品）流通
C2 [ C usually singular ] the number of people that a newspaper or magazine is regularly sold to（报纸杂志的）发行量，销售量
C2 [ U ] the movement of blood around the body（血液的）循环
The newspaper's circulation has dropped dramatically.
I heard that there are several stolen paintings in circulation.
Police are aware of the circulation of forged bank notes.