ME'DIUM, n. plu.mediums; media not being generally, though sometimes used. [L.] In philosophy, the space or substance through which a body moves or passes to any point. Thus either is supposed to be the medium through which the planets move; air is the medium through which bodies move near the earth; water the medium in which fishes live and move; glass a medium through which light passes; and we speak of a resisting medium, a refracting medium, &c.

1. In philosophy, the space or substance through which a body moves or passes to any point. Thus ether is supposed to be the medium through which the planets move; air is the medium through which bodies move near the earth; water the medium in which fishes live and move; glass a medium through which light passes; and we speak of a resisting medium, a refracting medium, a refracting medium, &c.
2. In logic the mean or middle term of a syllogism, or the middle term in an argument, being the reason why a thing is affirmed or denied. Nothing can be honorable that violates moral principle. / Dueling violates moral principle. / Therefore dueling is not honorable. / Here the second term is the medium, mean, or middle term.
3. Arithmetical medium, that which is equally distant from each extreme, or which exceeds the lesser extreme as much as it is exceeded by the greater, in respect of quantity, not of proportion. Thus, 9 is a medium between 6 and 12.
4. Geometrical medium, is that wherein the same ratio is preserved between the first and second terms, as between the second and third. Thus, 6 is a geometrical medium between 4 and 9. Encyc. In the three last senses or applications, mean is more generally used for medium.
5. The means or instrument by which any thing is accomplished, conveyed or carried on. Thus money is the medium of commerce; coin is the common medium of trade among all civilized nations, but wampum is the medium of trade among the Indian tribes, and bills of credit or bank notes are often used as mediums of trade in the place of gold and silver. Intelligence is communicated through the medium of the press.
6. The middle place or degree; the mean. The just medium of this case lies between pride and abjection. L'Estrange.
7. A kind of printing paper of middle size.

1. That which lies in the middle, or between other things; intervening body or quantity. Hence, specifically: (a) Middle place or degree; mean.
   
   

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

   (b) (Math.)

2. Having a middle position or degree; mean; intermediate; medial; as, a horse of medium size; a decoction of medium strength.
3. 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.

4. An average.
   
   
   [R.]

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

5. A trade name for printing and writing paper of certain sizes. See Paper.
6. The liquid vehicle with which dry colors are ground and prepared for application.
   
   

   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.