medium

1. (microbiology) A nutrient substance, commonly a solution or solid, for the growth of cells in vitro.Examples: "In some instances one can take advantage of differential carbohydrate fermentation capabilities of microorganisms by incorporating one or more carbohydrates in the medium along with a suitable pH indicator. Such media are called differential media (e.g., eosin methylene blue or MacConkey agar) and are commonly used to isolate enteric bacilli."

2. (biology, horticulture, etc.) A substance, structure, or environment in which living organisms subsist, grow or are cultured.Examples: "The density of the living medium of fishes exerts upon them a mechanical influence; they are, so to say, balanced in water, free to proceed in all planes of direction..."usually

3. (engineering) The materials used to finish a workpiece using a mass finishing or abrasive blasting process.

4. (countable, plural mediums or media) A liquid base which carries pigment in paint.countable

5. (painting) A means of expression, in the arts, such as a material (oil, pastel, clay, etc) or method or style (expressionism, jazz, etc).Examples: "Acrylics, oils, charcoal, and gouache are all mediums I used in my painting."; "Heretofore in following the course, the student has been confined to black and white in the medium of charcoal, pen and ink or pencil. The first introduction to color is by means of the Still Life painting class."; "It was the woodcut, however, that emerged as the favorite graphic medium of Expressionism. Rejecting the almost limitless pictorial possibilities of lithography, which had dominated printmaking during the nineteenth century, […]"

6. (countable, logic) The mean or middle term of a syllogism, that by which the extremes are brought into connection.countable