Definition from Wiktionary, the free dictionary
- (geomorphology) A geomorphologic unconformity marking a boundary between an upland region and a plane; sometimes marked by a series of waterfalls on rivers that cross it.
- (snowboarding) The imaginary line downhill that something falling downhill would naturally follow.
(geomorphologyfall line) A line marking a boundary between an upland region and a plane
(snowboardingfall line) Imaginary line downhill