名词
1. 堡垒;要塞
A fastness is a place, such as a castle, which is considered safe because it is difficult to reach or easy to defend against attack.
1. a strongly fortified defensive structure
Synonym: stronghold
2. the quality of being fixed in place as by some firm attachment
Synonym: fixednessfixityfixturesecureness
3. a rate (usually rapid) at which something happens
e.g. the project advanced with gratifying speed