- The line defining the lowest points along the length of a river bed or valley.
- A subterranean stream.
Origin of thalwegGerman Talweg, Thalweg : Tal, Thal, valley (from Middle High German tal, from Old High German) + Weg, way (from Middle High German wec, weg, from Old High German weg; see wegh- in Indo-European roots).
(plural thalwege or thalwegs)
- The alternative spelling talweg is consistent with the German spelling reform of 1901.
From 19th century German Thal (“valley") + Weg (“way, course")