"Pornai" is the Ancient Greek word for "prostitute" (porne, in the singular). It may also be translated as a “buyable woman.” From the Greek word pornai, we get the English word pornography.
Ancient Greek society was fairly open to the practice of the world's oldest profession. Prostitution was legal in Athens, for example, as long as the workers were slaves, freed women or Metics (foreigners in Ancient Greece who had limited rights, not unlike legal residents in the U.S.) These women had to register and were required to pay taxes on their earnings.
The Sex Workers of Ancient Greece
Pornai were generally the ordinary sex workers, from those who worked in brothels to streetwalkers who advertised their services out in the open. How open? In one innovative marketing strategy some pornai wore special shoes that imprinted a message in soft ground saying, "follow me"
Male prostitutes were called pornoi. These sex workers were typically clean-shaven, and though they did sleep with women, they primarily serviced older men.
Sex work had its own social hierarchy in Greek society. At the top were hetaerai, which means “female companion.” These were beautiful, often educated and artistic women who were essentially high-class courtesans. Greek literature has numerous references to famous hetaerai who cast their spells.
One reason for the prevalence of sex worker -- aside from the existence of slavery, which meant women could be forced into prostitution -- was that Greek men married comparatively late in life, often in their thirties. This created a demand, as younger men sought sexual experience before marriage. Another factor was the fact that adultery with a married Greek woman was considered a high crime. So it was far safer to hire a pornai or a heaerai than sleep with a married woman.
Source: The Cambridge Companion to Ancient Greek law, by Michael Gagarin, David J. Cohen.