It's unknown when the term was coin or by whom, but it existed at least before November 2016.The alternate name, syncoric, was coined on February 8, 2018 by Tumblr user identity-workshop. It was named after a moon of Uranus, as it is considered a subtype of uranic.
The first nocismasexual flag was created on November 5, 2016 by beyond-mogai-pride-flags. No meaning was given for the flag.
The second, and most commonly seen nocismasexual flag was created by Mod Hermy from pride-color-schemes on June 12, 2017. The blue being at the bottom represents discomfort/unwillingness to have a relationship with a cis woman. The rest of the colors being represents how the person can be comfortable and fine with other genders/people.
An alternate flag was created by Asphyn Falwell (Oddlyasphyn) on June 28, 2020 on the LGBTA+ wiki. The light pink triangle represents cis women. The dark pinkish-grey outline around the triangle represents the separation and disconnection between cis women to any other identity. Finally, the greys represent the gender spectrum.
Another alternate flag, based on the design of the original, was created on July 30, 2020 by Tumblr user Rainbowcoric. The black outer stripes, as well as the line striking through, represent the lack of attraction to cis women or the decision to not date cis women. The dark red represents cis women. The pink represent any kind of t4t (trans-for-trans) attraction. The white stripe represents the trans people using the label.