[icebraining]

Free Software, as defined by the FSF, includes both copyleft like the GPL and permissive licenses like BSD. Open Source, as defined by the OSI, does the same.

Essentially, it's Free Software any license that provides the following four freedoms:

    The freedom to run the program, for any purpose (freedom 0).
    The freedom to study how the program works, and change it so
                             it does your computing as you wish (freedom 1).
    The freedom to redistribute copies so you can help your neighbor (freedom 2).
    The freedom to distribute copies of your modified versions to others (freedom 3). 

Copyleft (like the GPL has) is a way to ensure that the four freedoms are transfered to any derivative work, but:

    A free license may also permit other ways of releasing them;
    in other words, it does not have to be a copyleft license.

https://www.gnu.org/philosophy/free-sw.html