An isolated hill or mountain rising abruptly from a surrounding plain, the remnant of more resistant rock after erosion has worn the landscape down. A monadnock is defined by its solitude and its story of endurance.

From the name of Mount Monadnock in New Hampshire, itself from an Abenaki (Algonquian) place-name often glossed as “isolated mountain.” Geology turned the proper noun into a common one when it needed a vivid label for a recurring landform: a mountain that remains when the world around it has been planed away.