1. (n.) A deep crevice or fissure, as in embankment\; one of the clefts or fissure by which the mass of a glacier is divided.

2. (n.) A breach in the levee or embankment of a river, caused by the pressure of the water, as on the lower Mississippi.

abysm abyss arroyo box canyon breach break chap chasm check chimney chink cleft cleuch clough col coulee couloir crack cranny crater crevice cut cwm deep defile dell depth dike ditch donga draw excavation fault fissure flaw flume fracture furrow gap gape gash gorge groove gulch gulf gully hole hollow incision joint kloof leak moat notch nullah opening pass passage pit ravine rent rift rime rupture scissure seam shaft slit slot split trench valley void wadi well yawning abyss