- A long, narrow, roughly straight channel or groove on the surface of a solar system body like a planet or moon.
- Variant of rill.
Origin of rilleGerman Rille; see rei- in Indo-European roots, from Low German rille; see rei- in Indo-European roots.
Ariadaeus, a lunar rille, photographed in 1969 by the crew of Apollo 10
- (planetology) A long, narrow depression in that resembles a channel, found on the surface of various lunar and planetary bodies.
From the German Rille (“channel”).