1. 固定性;稳定性;恒定性
If you talk about the fixity of something, you talk about the fact that it does not change or weaken.

1. the quality of being incapable of mutation

e.g. Darwin challenged the fixity of species

Synonym: immutabilityimmutableness

2. the quality of being fixed in place as by some firm attachment

Synonym: fastnessfixednessfixturesecureness