Elon Musk has branded “cisgender” a “heterophobic word”.

The Tesla billionaire, who bought Twitter in a $44 billion deal in 2022 before rebranding it under its current banner of X, sparked huge controversy by adding anyone who uses the phrases should be ashamed of themselves.

He messaged on X: “Cis is a heterophobic word. Shame on anyone who uses it.”

His comment sparked an immediate wave of outrage, with users explaining its meaning to the entrepreneur and others telling him it is “neither ‘heterophobic’ nor homophobic”.

Another fuming X user said Elon’s declaration was a sign he had “gotten so lost” – though others agreed with the SpaceX founder, saying ‘cis’ and ‘cisgender’ belonged to a tranche of “made-up words” from the so-called ‘woke’ movement.

Cisgender is defined as those whose internal sense of gender corresponds with the sex the person was identified as having at birth.

Dictionaries also states it is not meant to be used as an insult as it is intended to be used “neutrally”.

Elon has vowed to make X a platform for “free speech”, which he says should resemble a “town square” where everyone has a voice.

In June 2023, he appeared to have trolled actress Megan Fox, 37, after she was accused of forcing her sons to wear “girl’s clothes”.

He posted on X at the time, “Looking to hire a VP of Witchcraft and Propaganda.”

And in November last year, Elon was also accused of allowing anti-semitism to run rampant on X and even endorsing a hateful comment about Jews himself – which he denied.

The move caused many advertisers, including Walt Disney, to pull their content from the site, causing the social media company to lose millions of dollars.