I don't know history, but the Wikipedia definition is good: "In economics, a free market is a system in which the prices for goods and services are self-regulated by buyers and sellers negotiating in an open market. In a free market, the laws and forces of supply and demand are free from any intervention by a government or other authority, and from all forms of economic privilege, monopolies and artificial scarcities."

The "free" is on the forces of supply-and-demand, not a lack of regulations altogether (which is laissez-faire / anarchist). Wikipedia continues -- although with a bit of a non-sequitur in between, to explain that:

"All of these fields emphasize the importance in currently existing market systems of rule-making institutions external to the simple forces of supply and demand which create space for those forces to operate to control productive output and distribution."

Note that regulation is _external_ to supply-and-demand. It shouldn't interfere with the core concepts:

- Economic equilibrium

- Low barriers to entry

- Competition

- Spontaneous order

- Supply and demand