Elegender

Elegender or ethegender is a xenogender that is unable to be understood by either the individual or others; a gender that cannot be explained; a dainty, elegant, or delicate gender.

History
Elegender was coined before July 17, 2014 by robotxt on tumblr and posted to Pride-Flags-For-Us, a now-defunct MOGAI archive and flag-making blog.

Flag
The Elegender flag was coined before July 17, 2014 by robotxt on tumblr and posted to Pride-Flags-For-Us.

Resources
http://archive.is/jvjq0#selection-51.0-56.0