Why Do Trade Agreements Have to be "Free?"

Why can't the NYT just call the trade agreements being sent to the senate "trade" agreements? Why does it feel the need to mislead readers in the headline and several times in the article itself by calling them "free trade" agreements?

These deals do not free all trade. There will still be plenty of protectionist barriers left in place that will make it difficult for doctors, lawyers and other professionals from these countries from working in the United States. Furthermore the deals...