that which lies in the middle, or between other things; intervening body or quantity. hence, specifically: (a) middle place or degree; mean.-see mean.-the mean or middle term of a syllogism; that by which the extremes are brought into connection.-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.-an average.-a trade name for printing and writing paper of certain sizes. see paper.-the liquid vehicle with which dry colors are ground and prepared for application.-having a middle position or degree; mean; intermediate; medial; as, a horse of medium size; a decoction of medium strength.