fastness
noun /ˈfɑːstnəs/
/ˈfæstnəs/
(literary)- a place that is thought to be safe because it is difficult to get to or easy to defend synonym stronghold
- a mountain fastness
- The enemy retreated to their fastness in the mountains.
Oxford Collocations DictionaryFastness is used after these nouns:- mountain
Word OriginOld English fæstnes (see fast ‘quick’ and -ness).