medium2 plural media or mediums [countable]
a way of communicating information and news to people, such as newspapers, television etc [↪ media]:
Advertising is a powerful medium.
a way of expressing your ideas, especially as a writer or an artist
the novel as a medium for satire
the visual media (=painting and films)
a language that is used for teaching:
English is still the main medium of instruction in Nigeria.
money or other ways of paying for things
a substance or material in which things grow or exist:
a good growing medium for tomatoes
a substance through which a force travels