coincident with A relation that holds between two linear structures that are approximately parallel to each other for their entire length and where either the two structures are adjacent to each other or one is part of the other. Example: if we define region of chromosome as any subdivision of a chromosome along its long axis, then we can define a region of chromosome that contains only gene x as 'chromosome region' that coincident_with some 'gene x', where the term gene X corresponds to a genomic sequence.