If someone asked you to define "free market," could you?  Could you do it on the spot without recourse to dictionaries or other crutches?

The term "laissez-faire economy" might do as a first response.  But what does it mean?  In Capitalism: The Unknown Ideal Ayn Rand explains:

ased on a column in the Los Angeles Times, August 1962.

Colbert, chief adviser of Louis XIV, was one of the early modern statists. He believed that government regulations can create national prosperity and that higher tax revenues can be obtained only from the country's "economic growth"; so he devoted himself to seeking "a general increase in wealth by the encouragement of industry." The encouragement consisted of imposing countless government controls and minute regulations that choked business activity; the result was dismal failure.

Colbert was not an enemy of business; no more than is our present Administration. Colbert was eager to help fatten the sacrificial victims—and on one historic occasion, he asked a group of manufacturers what he could do for industry. A manufacturer named Legendre answered: "Laissez-nous faire!" ("Let us alone!")

But Legendre was hardly the first to express a hands-off idea.  In An Austrian Perspective on the History of Economic Thought, Rothbard tells us about Chuang Tzu (369-c.286 BC):

'There has been such a thing as letting mankind alone; there has never been such a thing as governing mankind [with success]'. Chuang Tzu was also the first to work out the idea of 'spontaneous order', independently discovered by Proudhon in the nineteenth century, and developed by F.A. von Hayek of the Austrian School in the twentieth. Thus, Chuang Tzu: 'Good order results spontaneously when things are let alone'.