Cisgender

Cisgender is a label that is used to indicate that the person labelled identifies with the gender they were designated at birth. It is a neologism coined as a counterpart (or antonym) to "transgender," and its first documented usage was on the Internet in 1994.

Cisgender is a more precise term than "gender-normative", i.e., the claim that someone has a "normal" gender for their assigned sex, as this can be confused with heteronormativity or the application of gender roles.

Etymology
The term is derived from a Latin preposition that indicates position relative to the speaker: cis means "on the same side", chosen by analogy to the existing word transgender, itself from trans which means "on the far side." In gender, this refers to whether your gender identity matches your gender designated at birth (i.e., designated female at birth, DFAB, or designated male at birth, DMAB) which helps smooth out any connotations involving "male-bodied" and "female-bodied" terms. Although the term cisgender is a neologism in English dating back to 1997, the use of the prefix 'cis-' in various contexts dates back to the 1700s, and has most commonly used in chemistry following the discovery of molecular chirality by Louis Pasteur

Use of "cis" as a prefix for words related to gender in fact predate this English usage, as the 1914 German text "Lexikon des gesamten Sexuallebens", by medical doctor and LGBTQ+ activist used the word "cisvestitismus" to refer to people who dress in accordance with the gender society gives them at birth.

The same terminology has a long history in other fields. In organic chemistry, for example, trans fatty acids are unsaturated fatty acids where the hydrogen atoms on either side of the double-bond lie across from one another, while cis fatty acids are unsaturated fatty acids where the hydrogen atoms on either side of the double-bond stand next to each other.

In geography, several areas use the term. Most European locations, such as Transoxiania (beyond the Oxus) and Cisalpine (this side of the Alps) use Rome as a reference point for historical reasons. One exception is Transylvania (beyond the Woods), which is from the point of view of Budapest. In South Africa under apartheid there were two "bantustans" on either side of the Great Kei River - Ciskei and Transkei.

Offensive?
Some people find "cisgender" to be offensive — where have we heard that before? Although many in the transgender community maintain that it is mostly transphobes, especially TERFs, who consider it a slur, there are others who have stated that "cis" is offensive for various reasons. Firstly, there are those who believe it is incompatible with the notion of a nonbinary view of gender. This would certainly lend a greater nuance to the debate, but would not make it offensive, merely overly simplistic.

Secondly, there are those who use the term to open a wider attack on transexuality as a whole, citing it as incompatible with radical feminist discourse. These people claim that "no one" has a gender, and that all gender is socially constructed. While it can be shown that gender roles and expectations are socially constructed and inherently harmful, this does not mean that gender identity is a myth, especially given that a great deal of evidence    points to it having a biological cause. It merely states that for some people, the way they were apparently born (physical sex) does not agree with how they see themselves (gender identity), and they wish to change. Everyone else is cis.

Or perhaps those who take offense with the terms are just cissies.

Some thin-skinned asshole who bought Twitter and who opened the floodgates for formerly-banned Nazis decided that using the term 'cis' repeatedly was a bannable offence.

Related terms

 * Cissexism, the belief that cisgender people are superior to transgender people. It is the equivalent of heterosexism regarding sexual orientations.
 * Cisgender privilege, the transgender analogue to male privilege, white privilege, able-bodied privilege, bourgeois-oppressor privilege, etc.