See morgan.
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cen·ti·mor·gan 'sen-tə-.mȯr-gən n a genetic unit equivalent to 1/100 of a morgan
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cen·ti·mor·gan (cM) (sen″tĭ-morґgən) one-hundredth (10−2) of a morgan; the unit of distance on a genetic map. The map distance between adjacent loci, expressed in centimorgans, is equal to the recombination frequency, expressed as a percentage; two loci are 1 cM apart if recombination is detected between them in one per cent of meioses. For nonadjacent loci the map distance can be greater than the recombination frequency, because recombination frequencies are not always additive. Called also map unit.Medical dictionary. 2011.