[run down] vt (ca. 1578) 1 a: to collide with and knock down b: to run against and cause to sink
2. a: to chase to exhaustion or until captured b: to trace the source of c: to tag out (a base runner) between bases on a rundown
3: disparage ~ vi 1: to cease to operate because of the exhaustion of motive power "the clock ran down"
2: to decline in physical condition or vigor