IPA: /ˈfæstnəs/
KK: /ˈfæstnəs/
A strong or secure place that is difficult to enter or attack, often used for protection.
The castle served as a fastness for the villagers during the invasion.
Fastness → It is formed from "fast" (from Old English *fæst*, meaning firm or secure) and "-ness" (meaning the state or quality of). The word "fastness" refers to the state of being firm or secure.
Think of the word 'fast' meaning firm or secure, and remember that 'fastness' describes the quality of being firm.