Don’t know how I missed this last year.
Below is a paste from that page. Note that originally these terms were only available in the USA but they now seem to be available here. Hooray!
Any attempt to define these terms (and even ‘male’ or ‘female’) is bound to be problematic. But if you are wondering what a cisgender person is, you probably ARE one. Most people on the planet are probably cisgender. That term could simply refer to a male-born or female-born person with a gender identification as a ‘traditional’ man or woman respectively, or someone who has no ‘gender issues.’ You get the idea.
Facebook’s new gender options
Here is a list of new gender options Facebook is making available:
Female to Male
Male to Female