From Nonbinary Wiki

    In 2013, a user of the social media site Tumblr coined an abbreviation of nonbinary or N.B., "enby." This word and how people have come to use it is discussed below.[1][2][3]

    1. @cassolotl on Tumblr (September 2013)
    2. vector (revolutionator). Untitled post, September 2013. revolutionator's blog is password-protected, but the post has been reblogged many times, eg: here, date unknown, captured April 2016.
    3. "Queer Etymology: Enby". Androgyne of the Archeart. 16 December 2019. Retrieved 20 September 2020.