|the offspring of a zebra and a donkey.|
|a screen or mat covered with a dark material for shielding a camera lens from excess light or glare.|
|1.||the transport of oxygenated blood through the arteries to the capillaries, where it nourishes the tissues, and the return of oxygen-depleted blood through the veins to the heart, where the cycle is renewed|
|2.||the flow of sap through a plant|
|3.||any movement through a closed circuit|
|4.||the spreading or transmission of something to a wider group of people or area|
|5.||(of air and water) free movement within an area or volume|
|6.||a. the distribution of newspapers, magazines, etc|
|b. the number of copies of an issue of such a publication that are distributed|
|a. a book loan, as from a library lending department|
|b. each loan transaction of a particular book|
|c. the total issue of library books over a specified period|
|8.||a rare term for circulating medium|
|a. (of currency) serving as a medium of exchange|
|b. (of people) active in a social or business context|
circulation cir·cu·la·tion (sûr'kyə-lā'shən)
movement in a circle or circuit, especially the movement of blood through bodily vessels as a result of the heart's pumping action.
|circulation (sûr'kyə-lā'shən) Pronunciation Key
The flow of fluid, especially blood, through the tissues of an organism to allow for the transport and exchange of blood gases, nutrients, and waste products. In vertebrates, the circulation of blood to the tissues and back to the heart is caused by the pumping action of the heart. Oxygen-rich blood is carried away from the heart by the arteries, and oxygen-poor blood is returned to the heart by the veins. The circulation of lymph occurs in a separate system of vessels (the lymphatic system). Lymph is pumped back to the heart by the contraction of skeletal muscles.
Also, into circulation. In business or social life, especially after a period of absence. For example, After a month in the hospital Bill was eager to get back in circulation. The antonym is out of circulation, as in Since we had twins we've been out of circulation, but we're hoping to get out more often soon. These expressions, dating from the first half of the 1900s, employ circulation in the sense of "making the rounds among people," a usage dating from the 1600s.