Me·di·um n.; pl. L. Media E. Mediums
 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. See Mean. (c) 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.
 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.