French 'butte' (mound), brought to English by fur trappers describing the flat-topped hills of the American West.
An isolated steep-sided flat-topped hill, smaller than a mesa, common in arid regions of the American West.
From French 'butte' meaning 'mound, knoll,' from Old French 'but' (goal, target mound). French-Canadian fur trappers applied the word to the dramatic flat-topped hills of the western plains. Entered English through the Lewis and Clark expedition