is a Latin
word meaning "on the same side" and is the opposite of trans
. See Ciskei
, also Cisalpine Gaul
and Transalpine Gaul.
In chemistry, a double bond in which the greater radical on both ends is on the same side of the bond is called cis
. Compare with trans
In the example shown on the right, both hydrogen molecules, (and both fluorine molecules) are on the same side of the carbon chain. As the carbons are joined by a double bond, these cannot rotate around the molecule.
See Geometric isomerism for more on this.
In genetics, cis- is a prefix used in terms such as "cis-regulation" to signify the co-location of two or more genes on the same chromosome of a homologous pair.
In mathematics, eix = cos x + i sin x (see Euler's formula). Cis is a now seldom used abbreviation for "cosine plus i sine" (of x). Usually eix or exp(ix) is best used.
Unrelated to the above, CIS is an acronym for Commonwealth of Independent States.