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: (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.

Me"di*um, a. Having a middle position or degree; mean; intermediate; medial; as, a horse of medium size; a decoction of medium strength.