a sunken or depressed geological formation

not solid; having a space or gap or cavity

remove the interior of

remove the inner part or the core of

a hole made by an animal, usually for shelter

a hole in the ground made by gophers

(geology) a hollow (typically filled by a lake) that results from the melting of a mass of ice trapped in glacial deposits

a sizeable hole (usually in the ground)

a pit or hole produced by wear or weathering (especially in a road surface)