dip [dips](lower section of a road or geological feature)
noun
[UK: dɪp] [US: ˈdɪp] pothole [potholes](pit in the bed of a stream)
noun
[UK: ˈpɒt.həʊl] [US: ˈpɒthoʊl] trough [troughs](a long, narrow depression between waves or ridges)
noun
[UK: trɒf] [US: ˈtrɒf] | 