Definition of mediums:
(n) :
(often treated as uncountable) The means and institutions for publishing and broadcasting information.
(n) :
(often treated as uncountable) The totality of content items (television shows, films, books, photographs, etc.) which are broadcast or published.
(n) :
(usually with a definite article; often treated as uncountable) The journalists and other professionals who comprise the mass communication industry.
(n) :
(computing) Files and data comprising material viewable by humans, but usually not plain text; audiovisual material.
(n) :
(anatomy) The middle layer of the wall of a blood vessel or lymph vessel which is composed of connective and muscular tissue.
(n) :
(linguistics, dated) A voiced stop consonant.