a valley that resembles the letter U

plural of trough shell

Any clam of the family Mactridae.

plural of wine trough

Alternative form of winetrough

plural of Gunn-Peterson trough

A feature in astronomical spectrometry of distant light, caused by the Reionization Era's absorption of UV light, leaving a gap in the spectrum.

Resembling or characteristic of a trough.

Without a trough.

plural of Troughton level