1 [singular, uncountable]HBH
the movement of blood around your body:
Exercise improves the circulation.
Doctors had to remove her leg because of bad circulation.
the exchange of information, money etc from one person to another in a group or society
in/out of circulation
Police believe there are thousands of illegal guns in circulation.
The book was taken out of circulation.
remove/withdraw something from circulation
The Treasury Department plans to remove older coins from circulation and replace them with new ones.
3 [countable, usually singular]TCN
the average number of copies of a newspaper or magazine that are usually sold each day, week, month etc
The newspaper has a daily circulation of 55,000.
4 [uncountable and countable]
the movement of liquid, air etc in a system:
Let's open the windows and get some circulation in here.
when someone takes part or does not take part in social activities at a particular time:
Sandy's out of circulation until after her exams.