Definition of butte

i. A conspicuous hill or small mountain with relatively steep slopes or precipitous cliffs, often capped with a resistant layer of rock, and representing an erosion remnant carved from flat-lying rocks. The summit is smaller in extent than that of a mesa; many buttes in the arid and semiarid regions of the Western United States result from the wastage of mesas.

Synonym of: mesa-butte

ii. An isolated hill having steep sides and a craggy, rounded, pointed, or otherwise irregular summit; e.g., a volcanic cone (such as Mount Shasta, CA, formerly known as Shasta Butte) or a volcanic butte. Etymol: French, knoll, hillock, inconspicuous rounded hill; rising ground. Pron: bewt.

Ref: AGI