Cisgender

Most people are cisgender. It is a plain descriptive term, roughly as loaded as "right-handed".

If you were recorded as female at birth and you are a woman, you are a cisgender woman. If you were recorded as male at birth and you are a man, you are a cisgender man. That is the whole definition. It says nothing about your sexual orientation, your gender expression, how masculine or feminine you are, or whether you follow any gender norms at all. A cisgender man in a dress is still cisgender.

The short form is cis, and it works the same way trans does: an adjective placed before the noun. "Cis women" and "cisgender people" are correct. "Cis" as a noun is not.

Flag

There is no cisgender pride flag, and this is not an oversight. Pride flags exist to make marginalised groups visible to each other. Cisgender is the unmarked majority, so there is nothing to signal.

Cis is Latin for "on this side of", the direct counterpart to trans, "across" or "on the other side of". The pair comes from chemistry and from Roman geography, where Cisalpine Gaul was the side of the Alps nearer Rome and Transalpine Gaul was the far side. Neither prefix carries a judgement: they are directions.

The Oxford English Dictionary cites a 1994 post to the Usenet newsgroup alt.transgendered by Dana Leland Defosse as the earliest use of "cisgender" in English. The underlying cis/trans pairing is older than that: the historian Avery Dame-Griff has traced a cis/trans dichotomy applied to gender in German sexological writing as far back as 1914, and the German sexologist Volkmar Sigusch used zissexuell in academic work in the early 1990s. The English word spread through trans community writing over the following decade, entered the Oxford English Dictionary in 2015, and was added to Merriam-Webster in 2017.

Why does a word for this exist?

Because the alternative was worse. Before cisgender, the way to describe a non-trans person in English was "normal", or "biological woman", or "real man". Every one of those makes a claim: that trans people are abnormal, non-biological or unreal. Naming the majority position removes that claim by making both sides describable.

This is a very ordinary move in language. Heterosexual exists so that homosexual is not the only labelled category. Right-handed exists for the same reason. Naming the default is what stops the default from being invisible, and invisible defaults are how "man" quietly comes to mean "not a trans man".

Myth: cisgender is a slur

It is a descriptive adjective with a Latin prefix, coined in academic writing and now in every major English dictionary. It has no history of being used to demean anyone, and it does not name anything shameful. The reaction is usually less about the word and more about the discomfort of being categorised at all, which is an experience trans people have every day.

Myth: nobody asked to be called this

Nobody asked to be called heterosexual either. Descriptive categories are not opt-in. If the objection is that a word implies trans identity is equally normal, that is not a misreading of the word, it is what the word is for.

Myth: cisgender means conforming to gender roles

It does not. Cisgender is about identity matching assignment, and nothing else. Butch cis lesbians, feminine cis men, and cis people with no interest in gendered expectations are all cisgender.

Myth: you cannot be cisgender and intersex

You can. An intersex person whose gender identity matches the sex they were assigned at birth may describe themselves as cisgender, though many intersex people find neither cis nor trans fits well and prefer to leave the question alone. Follow the person's own usage.

Myth: cisgender is an insult when used in arguments

A neutral word can be used rudely, like any other. "Cis people should listen here" is a claim about a conversation, not an insult. If the word is doing work you dislike, the disagreement is with the claim, not the vocabulary.