medium.

The material of the surrounding environment, e.g. solid, liquid, gas, vacuum, or a specific substance such as a solvent.

The materials or empty space through which signals, waves, or forces pass.

A format for communicating or presenting information.

A nutrient substance, commonly a solution or solid, for the growth of cells in vitro.

A substance, structure, or environment in which living organisms subsist, grow or are cultured.

A means, channel, agency or go-between through which communication, commerce, etc is conveyed or carried on, or by which an aim is achieved.

Cable TV is an inexpensive advertising medium.

The materials used to finish a workpiece using a mass finishing or abrasive blasting process.

A liquid base which carries pigment in paint.

A means of expression, in the arts, such as a material (oil, pastel, clay, etc) or method or style (expressionism, jazz, etc).

Acrylics, oils, charcoal, and gouache are all mediums I used in my painting.

The mean or middle term of a syllogism, that by which the extremes are brought into connection.

Someone who conveys information from the spirit world.

A middle place or degree.

a happy medium

An average; sometimes the mathematical mean.

Anything of a middle rank or position.

One of several common sizes to which an item may be manufactured, smaller than a large but larger than a small.

An item labelled or denoted as being that size.

One who fits an item of that size.

A half-pint serving of Guinness (or other stout in some regions).

Arithmetically average.

Of intermediate size, degree, amount etc.

Of meat, cooked to a point greater than rare but less than well done; typically, so the meat is still red in the centre.

That is medium (the manufactured size).

To a medium extent.