Definition of cis- in English:



  • 1On this side of; on the side nearer to the speaker.

    Often contrasted with trans- (sense 1) or ultra- (sense 2)

    • ‘cislunar’
    • ‘It is definitely one of the premier geological wonders of cislunar space.’
    • ‘The waters of cis-equatorial seas.’
    • ‘The generally accepted cis-oceanic ideas.’
    1. 1.1 historical On the side nearer to Rome.
      • ‘cisalpine’
    2. 1.2(of time) closer to the present.
      • ‘I place him confidently not a trans-, but cis-reformation-man.’
  • 2Referring or relating to people whose sense of personal identity and gender corresponds with their birth sex.

    Compare with trans- (sense 3)

    • ‘cissexism’
  • 3usually cis-Chemistry
    Denoting molecules with cis arrangements of substituents.

    • ‘Full X-ray crystallographic data were published (or deposited) for some of the isomerizing cis- or trans-cinnamic acids.’
    • ‘Analogous to other fruits, cis-neurosporene, neurosporene, carotene, and cis- carotene were also present among the visible light-absorbing compounds.’
    • ‘Similar effects were seen with 13 - cis-retinoic acid.’
    • ‘Trans-fatty acids raise LDL cholesterol levels and lower HDL cholesterol levels relative to cis-unsaturated fatty acids and may increase the risk of diabetes.’
    • ‘This enzyme inserts a cis-double bond at carbon 9.’


From Latin cis ‘on this side of’.