
1) German geographic term
Found on
https://www.crosswordclues.com/clue/inselberg

(from German Insel, `island,` and Berg, `mountain`), isolated hill that stands above well-developed plains and appears not unlike an island rising ... [6 related articles]
Found on
http://www.britannica.com/eb/a-z/i/25

A steep ridge or hill left when a mountain has eroded and found in an otherwise flat, typically desert plain.
Found on
http://www.encyclo.co.uk/local/22291

A German term used to describe a steep-sided hill composed of rock that rises from a pediplain.
Found on
http://www.physicalgeography.net/physgeoglos/i.html

Prominent steep-sided hill of resistant solid rock, such as granite, rising out of a plain, usually in a tropical area. Its rounded appearance is caused by so-called onion-skin weathering (exfoliation), in which the surface is eroded in successive layers. The Sugar Loaf in Rio de Janeiro harbour in Brazil, and Ayers Rock in Northern Ter...
Found on
https://www.encyclo.co.uk/local/21221

Isolated, usually steep-sided hill or mountain rising from a plain.
Found on
https://www.encyclo.co.uk/local/22222

monadnock (def. 1).
Found on
https://www.infoplease.com/dictionary/inselberg
No exact match found.