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a prefix occurring in loanwords from Latin meaning “on the near side of” (cisalpine); on this model, used in the formation of compound words (cisatlantic).
Chemistry. a specialization of this denoting a geometric isomer having a pair of identical atoms or groups attached on the same side of two atoms linked by a double bond.
Compare trans- (def 2).
< Latin; akin to here Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for cis-


on this or the near side of cisalpine
(often in italics) indicating that two groups of atoms in an unsaturated compound lie on the same side of a double bond cis-butadiene Compare trans- (sense 5)
Word Origin
from Latin
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Word Origin and History for cis-
prefix meaning "on the near side of, on this side of," from L. preposition cis "on this side of," related to citra (adv.) "on this side." Opposed to trans- or ultra-.
Online Etymology Dictionary, © 2010 Douglas Harper
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cis- in Medicine

cis- pref.
Often cis- Having a pair of identical atoms or groups on the same side of a plane that passes through two carbon atoms linked by a double bond: cis-butene.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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