The sale of goods directly to the consumer, encompassing the storefronts, mail-order, websites, etc., and the corporate mechanisms, branding, advertising, etc. that support them.
Retail price; full price; an abbreviated expression, meaning the full suggested price of a particular good or service, before any sale, discount, or other deal.
Source: https://en.wiktionary.org/wiki/retail#English
The way I hear it recently is like:
Institutions buy Bitcoin all the time. Retail don't have much say.
Here, they seem to refer to "retail" as being "the common man", or individuals, rather than having anything to do with a "retail store" or "full price".
Why do they call "non-institutions" retail?