cwm       
noun [ C ]  geology specialized uk/kʊm/ us/kʊm/
 (尤指威尔士山中的)围谷,圈谷
a hollow area almost surrounded by steep slopes at the top of a glaciated valley, especially in the Welsh mountains
  The scalloped cwms of the Brecon Beacons are a favourite launching site for hang-gliders and parascenders. 布雷肯比肯斯山中的圈谷有着扇贝形的边缘,大受滑翔机和牵引升空跳伞爱好者的青睐。 
 Synonym: cirque 
 - More examples
- My eyes were drawn up and across the cwm to the giant cliffs of Lliwedd soaring up to jagged summits.
- That's the cwm where the yew trees grow.
- Finally we breasted the saddle in the lower ridge, what in the Welsh mountains we would call the cwm.
- This was the approach for the early climbing expeditions, who knew this as the North Cwm.