fastness
(noun)
noun
1. a rate (usually rapid) at which something happens
Similar word(s): speed, swiftness
Definition categories: attribute, pace, rate
2. the quality of being fixed in place as by some firm attachment
Similar word(s): fixedness, fixity, fixture, secureness
Definition categories: attribute, immovability, immovableness
3. a strongly fortified defensive structure
Similar word(s): stronghold