n. 1. the difference between the abscissas of two points; the ratio of rise to run gives the slope of the line segment joining the points. 2. vb. (of a sequence of data from a distribution) to be divisible into successive strings of observations with a common property; for example, the sequence 12, 16, 8, 14, 17, 11, 3, 5, 9, 18, 10, 8 runs with respect to parity.