Butte - Isolated hill with steep, often vertical sides and a small, relatively flat top

"In geomorphology, a butte is an isolated hill with steep, often vertical sides and a small, relatively flat top; buttes are smaller landforms than mesas, plateaus, and tablelands. The word butte comes from a French word meaning "small hill"; its use is prevalent in the Western United States, including the southwest where mesa is used for the larger landform. Because of their distinctive shapes, buttes are frequently landmarks in plains and mountainous areas. In differentiating mesas and buttes, geographers use the rule of thumb that a mesa has a top that is wider than its height, while a butte has a top that is narrower than its height. - Wikipedia"