in the middle between a larger and smaller size, amount, length, temperature, etc.

a way of communicating information, etc. to people

something that is used for a particular purpose

English is the medium of instruction.

Video is a good medium for learning a foreign language.

the material used for storing computer files, such as on magnetic tape or discs

Copy files to and from the device as you would with any other storage medium.

the material or the form that an artist, a writer or a musician uses

Watercolour is his favourite medium.

a substance that something exists or grows in or that it travels through

The bacteria were growing in a sugar medium.

a person who claims to be able to communicate with the spirits of dead people

LEARNit Dictionary