thalweg

noun

thal·​weg

ˈtälˌveg,

-vāḵ

plural -s

1

a

: a line following the lowest part of a valley whether under water or not

b

: the line of continuous maximum descent from any point on a land surface or one crossing all contour lines at right angles

c

: subsurface water percolating beneath and in the same direction as a surface stream course

2

: the middle of the chief navigable channel of a waterway which constitutes a boundary line between states

Word History

Etymology

German talweg (formerly spelled thalweg), from tal valley (from Old High German) + weg way, path, from Old High German

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