CIS

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For acronym CIS, see CIS.

Latin word Cis

Cis is a Latin word meaning "on the same side [of]" or "on this side [of]", and is the opposite of trans. Its uses include:

• In chemistry, a double bond (or ring) in which the greater radical on both ends is on the same side of the bond (or face of the ring) is called cis. Compare with trans. In the example shown on the right, both hydrogen atoms, (and both fluorine atoms) 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 also Geometric isomerism.

• 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. The action of molecules is also described in these terms (see Cis-acting).

• In geography, placenames beginning with Cis- convey the meaning "on this side of". Examples include Ciskei (referring to the Kei River), Cisleithania (Leitha), Cisalpine Gaul (Alps), Cisjordan (the region around Jordan). The antonym is Trans-.

• In astronomy cislunar means outer space between the Earth and the Moon. Translunar is its antonym.

• In medicine and sociology, Cisgender and cissexual are the opposite of Transgender and transsexual, respectively. Both describe people whose gender identity matches their physical and/or assigned sex.

Uses not derived from Latin

Other meanings of cis, not related to the Latin term, are:

• In mathematics, r cis θ is a now rarely used abbreviation for r(cos θ + i sin θ), which is equal to r(e^iθ) (see Euler's formula).

• In music, Cis is another name for the note C♯ (C-sharp).

• Cis is also the name of a commune in the province of Trento, northern Italy.

• The character cis from the cartoon Program (The Animatrix).

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