Lunettian is a non-binary xenogender in the celestial gender system. It is linked to a soft, celestial, feminine energy. It is never hyper feminine and it is not female-aligned, it's simply linked. Lunettian people may feel different amounts of feminine energy at different times.
The term lunettian and the flag were created by the Tumblr user Juparian on Oct 31, 2017. An alternate version of the flag was designed by System-Lgbt in October of 2018. The colors were chosen to resemble the colors of the moon.
The root of lunettian is 'lune' which means something related to the moon. The moon has historically been associated with femininity and feminine energy.