The definition doesn’t say anything about legal, illegal or regulated.
So, you have a different definition to most economists.
It is a market where prices are self regulated by supply and demand, without coercion. It perfectly suits for the exchange of of FIATs (or crypto) between parties.
You can call it whatever you want, anyways.
I recommend “Free to Choose” from Friedman as starting point.
You're mistaken. Most economists understand the difference between a free market and a black market in the same way that I do (I am an economist myself). The very definition of free market that you quoted implies the existence of a legal framework and of an authority with coercive power, since some behaviours are prohibited:
"In a free market, the laws and forces of supply and demand are free from any intervention by a government or other authority other than those interventions which are made to prohibit market coercions. Examples of such prohibited market coercions include: economic privilege, monopolies, and artificial scarcities."
Further, a market in which fraudsters can commit fraud with impunity is also not a free market but a dysfunctional market.
At any rate, the notion of free market is only vaguely defined, as it's not an important theoretical construct in economics.
As far as crypto-currency markets are concerned, these are not a single market, but many different markets, some of which are heavily regulated, so it's hard to argue that it's a free market.
It is a market where prices are self regulated by supply and demand, without coercion. It perfectly suits for the exchange of of FIATs (or crypto) between parties.
You can call it whatever you want, anyways.
I recommend “Free to Choose” from Friedman as starting point.