circulation (Noun) — The dissemination of copies of periodicals (as newspapers or magazines).
circulation (Noun) — Movement through a circuit; especially the movement of blood through the heart and blood vessels.
circulation (Noun) — (library science) the count of books that are loaned by a library over a specified period.
circulation (Noun) — Number of copies of a newspaper or magazine that are sold. ex. "by increasing its circulation the newspaper hoped to increase its advertising"
circulation (Noun) — Free movement or passage (as of cytoplasm within a cell or sap through a plant). ex. "ocean circulation is an important part of global climate" ex. "a fan aids air circulation"
circulation (Noun) — The spread or transmission of something (as news or money) to a wider group or area.