What is "circulating medium"

Medium \Me"di*um\, n.; pl. L. Media, E. Mediums. [L. medium the middle, fr. medius middle. See Mid, and cf. Medius.]

1. That which lies in the middle, or between other things; intervening body or quantity. Hence, specifically:

   1. Middle place or degree; mean.

      The just medium . . . lies between pride and abjection.
      --L'Estrange.

   2. (Math.) See Mean.

   3. (Logic) The mean or middle term of a syllogism; that by which the extremes are brought into connection.

2. A substance through which an effect is transmitted from one thing to another; as, air is the common medium of sound. Hence: The condition upon which any event or action occurs; necessary means of motion or action; that through or by which anything is accomplished, conveyed, or carried on; specifically, in animal magnetism, spiritualism, etc., a person through whom the action of another being is said to be manifested and transmitted.

   Whether any other liquors, being made mediums, cause a diversity of sound from water, it may be tried.
   --Bacon.

   I must bring together All these extremes; and must remove all mediums.
   --Denham.

3. An average. [R.]

   A medium of six years of war, and six years of peace.
   --Burke.

4. A trade name for printing and writing paper of certain sizes. See Paper.

5. (Paint.) The liquid vehicle with which dry colors are ground and prepared for application.

6. (Microbiology) A source of nutrients in which a microorganism is placed to permit its growth, cause it to produce substances, or observe its activity under defined conditions; also called culture medium or growth medium. The medium is usually a solution of nutrients in water, or a similar solution solidified with gelatin or agar.

7. A means of transmission of news, advertising, or other messages from an information source to the public, also called a news medium, such as a newspaper or radio; used mostly in the plural form, i. e. news media or media. See 1st media[2].

   Circulating medium, a current medium of exchange, whether coin, bank notes, or government notes.

   Ethereal medium (Physics), the ether.

   Medium of exchange, that which is used for effecting an exchange of commodities -- money or current representatives of money.

Circulate \Cir"cu*late\, v. i. [imp. & p. p. Circulated; p. pr. & vb. n. Circulating.] [L. circulatus, p. p. of circulare, v. t., to surround, make round, circulari, v. i., to gather into a circle. See Circle.]

1. To move in a circle or circuitously; to move round and return to the same point; as, the blood circulates in the body.
   --Boyle.

2. To pass from place to place, from person to person, or from hand to hand; to be diffused; as, money circulates; a story circulates.

   Circulating decimal. See Decimal.

   Circulating library, a library whose books are loaned to the public, usually at certain fixed rates.

   Circulating medium. See Medium.