Mē'di-ŭm, n.

n.; Lat. pl. MĒ'DI-Ā, Eng. pl. MĒ'DI-ŬMS. [Lat. medium, the middle, from medius, middle.] 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 of this case 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. An intervening or pervading substance; that through which, in any case, motion must take place, action be communicated, &c.; hence, the condition upon which any event or action occurs; necessary means of motion or action; instrumentality of communication; agency of transmission; that through or by which any thing is accomplished, conveyed, or carried on; specifically, in animal magnetism, spiritualism, &c., a person through whom the action of another being is said to be manifested and transmitted.
3. A kind of printing paper of middle size, about twenty-three inches long and eighteen inches wide.
4. (Paint.) The liquid vehicle with which dry colors are ground and prepared for the use of the painter.

Circulating medium, that which is commonly received as the representative of the value of articles bought and sold, and is used in making exchanges; coin and bank-notes or other paper convertible into coin on demand; currency. — Ethereal medium (Physics), ether. See ETHER.