The definition of stable is something steady that is not prone to change, someone who is level headed and who isn't subject to wild swings of emotion.
The definition of steadfast is fixed, firm and staying strong.
Not easily excited or upset:
Consistently reliable, especially because of resistance to outside pressures
Find another word for steady-going. In this page you can discover 6 synonyms, antonyms, idiomatic expressions, and related words for steady-going, like: stable, steadfast, steady, continue, dependable and rock-steady.