- Depression between hills - The space inclosed between ranges of hills or mountains;
the strip of land at the bottom of the depressions intersecting a
country, including usually the bed of a stream, with frequently broad
alluvial plains on one or both sides of the stream. Also used
figuratively. - The place of meeting of two slopes of a roof, which have
their plates running in different directions, and form on the plan a
reentrant angle. - The depression formed by the meeting of two slopes on a
flat roof.