Meaning of “stable” - Learner’s Dictionary

stable

adjective uk us /ˈsteɪbl/
SITUATION

not likely to change or end suddenly:

a stable relationship
The doctor said his condition was stable.
OBJECT

fixed or safe and not likely to move:

Be careful! That chair isn't very stable.
PERSON

mentally calm and not easily upset

→ Opposite unstable

(Definition of “stable adjective” from the Cambridge Learner’s Dictionary © Cambridge University Press)