The researcher who invented the term 'cisgender' has hit back at "cowardly" Elon Musk for calling the term a slur. 'Cis' or 'cisgender' was coined by now-retired researcher Dana Defosse. They are used to describe someone whose gender identity aligns with the sex they were assigned at birth. It is not offensive or intended to be used as an insult. Defosse first used the term in a 1994 internet forum, before being added to the Oxford English Dictionary much later in 2015. In an essay for HuffPost, Defosse explained how she invented the term: "I knew that in chemistry, molecules with atoms grouped on the same side are labelled with the Latin prefix ‘cis–,’ while molecules with atoms grouped on opposite sides are referred to as ‘trans–.’ So, cisgender. It seemed like a no-brainer," she wrote. On Wednesday (21 June), Musk responded to a user who claimed to have been harassed by trans rights activists. Twitter user James Esses said he "rejected" the terms after receiving "a slew of messages from trans activists calling me ‘cissy’ and telling me that I am ‘cis’ ‘whether or not I like it.’" In response, Musk tweeted: "Repeated, targeted harassment against any account will cause the harassing accounts to receive, at minimum, temporary suspensions. The words “cis” or “cisgender” are considered slurs on this platform." Sign up for our free Indy100 weekly newsletter The tech mogul's response left many social media users baffled, with Defosse saying it came as no surprise after his "ghastly history of attacking trans people." “The post on Twitter has degenerated into a sort of free-for-all for antisemitic and racist tropes, so it sort of fits in with the direction that platform is going," Defosse said. "The fact is, whether or not somebody identifies as cisgender doesn’t negate the fact that cisgender identity is a valid construct. It exists, and it has meaning in how we operate in the world." The retired researcher went on to call his censorship attempt "cowardly". "Banning use of a word that’s part of our daily vocabulary around the world, that appears in the Oxford English Dictionary, it’s a cowardly and futile attempt to censor an idea which is, in my opinion, way bigger and more enduring than anything Musk could hope to offer," she added. Have your say in our news democracy. Click the upvote icon at the top of the page to help raise this article through the indy100 rankings.