1 a movement to and fro, or from and back to a starting point, esp. of a fluid in a confined area or circuit. b the movement of blood from and to the heart. c a similar movement of sap etc.
2 a the transmission or distribution (of news or information or books etc.). b the number of copies sold, esp. of journals and newspapers.
3 a currency, coin, etc. b the movement or exchange of this in a country etc.
Phrases and idioms:
in (or out of) circulation participating (or not participating) in activities etc.
Etymology: F circulation or L circulatio f. circulare CIRCULATE
Useful english dictionary. 2012.