My Grandma will always be steadfast in her ways. {steadfast means to believe in one thing/it depends what it is, because you can be steadfast in a few different things at once/and not change the way...
The soldiers were able to gain victory after a hard fought battle because they were steadfast in their resolve.
The columns stood steadfast and resolute.
there is no root word in a compound word The two root words are stead (place) and fast (fixed, unmoving)
yatsiv (יציב)