What does cis mean?
Cis is a modern abbreviation of cisgender, an adjective describing a person whose gender identity aligns with the sex they were assigned at birth — essentially, anyone who is not transgender. The term emerged in academic writing in the late twentieth century and entered everyday use during the 2010s as discussions of gender identity became more widespread. Used neutrally in medical, sociological, and LGBTQ+ contexts ('a cis woman', 'cis and trans participants'), it can nonetheless carry political charge outside those settings, since it names a group that previously went unlabelled. Beyond gender, cis survives from classical Latin, where it meant 'on this side of', giving rise to terms like Cisalpine Gaul and, in organic chemistry, cis isomers, whose atoms sit on the same side of a bond. Knowing the word helps readers navigate contemporary conversations about identity and science alike.
Short for cisgender: describing a person whose gender identity matches the sex they were assigned at birth.
"Most participants in the study identified as cis."
On this side of; nearer (used especially in scientific and geographical terminology, as in cisalpine).
"The compound exists as a cis isomer, with both chlorine atoms on the same side of the ring."
The word 'cis' is over 2,000 years old in spirit — ancient Romans used the prefix to mean 'on this side of', as in Cisalpine Gaul — but it only became an everyday English word in the 2010s.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cis
Cis comes from Latin, where cis was a preposition and prefix meaning 'on this side of', used in phrases such as 'cis Alpes' (this side of the Alps), whence Cisalpine Gaul. English borrowed the prefix early on in geographic compounds like cisatlantic and later in chemistry's cis/trans notation for stereoisomers. The gender-related sense arose in the 1990s within academic sexology, coined as the natural antonym of 'transgender' by analogy with that same Latin pairing, and was clipped to 'cis' in common usage by the 2010s.
How cis is actually used
'Cis' is neutral descriptive vocabulary in academic, medical, and LGBTQ+ contexts, though it can be perceived as politically charged in casual debate, where some object to its use. It is informal as a standalone word; 'cisgender' is fuller and more formal. The chemistry sense is unrelated in meaning but shares the same Latin root.
Easily confused with cis
'Sis' is an informal term for a sister, while 'cis' is an abbreviation of 'cisgender', describing someone whose gender identity matches their birth-assigned sex.