Stability
Part of speech: noun
Definition: The condition of being stable. The tendency to recover from perturbations.
Example sentence: You get a reputation for stability if you are stable for years.
Constancy
Part of speech: noun
Definition: The quality of being constant; steadiness or faithfulness in action, affections, purpose, etc.An unchanging quality or characteristic of a person or thing.
Example sentence: Trust is not simply a matter of truthfulness, or even constancy. It is also a matter of amity and goodwill. We trust those who have our best interests at heart, and mistrust those who seem deaf to our concerns.