A commonly posed question, worthy of a universal and definitive answer.
However, media is not always comprehensively or easily defined.
Research would suggest that the context of definition, significantly impacts how the term media is defined. For instance, a public relations practitioner will group various mass and niche communications technologies and businesses into ‘target media channels’. Whereas an advertiser and media planner will define ‘media types or categories’, such as print, broadcast, outdoor, online, with a view to creating target channels for campaigns.
But how can you define a term by using a term?
I guess it comes down to whether it is a noun or an adjective.
These are just some of the definitions proposed for media. Which one do you think is best?