The configuration of an organic molecule containing a double bond between two carbon atoms, where the largest, most complex R groups are on the same side: H H / C=C / H3C CH3 -OR-The configuration of an organic molecule containing a ring, where the largest, most complex R groups are on the same side: H H | ___ / | // \ [ring viewed edge-on] | \___/ / | /--- H3C CH3 | H3C CH3 These configurations are the opposite of trans configuration. A genetics term meaning an event or a gene whose action occurs on the same chromosome. Two mutations in different genes coding for the same phenotype which are on the same chromosome (as opposed to the trans configuration where each homologue has one of the mutations).