adjective
stable
STAY-buhl/ˈsteɪbl/
Firm, steady, or unlikely to change or deteriorate.
The stable stool supports a full glass without tilting.

Etymology
The Latin adjective carries the image of being able to stand. Physical resistance to falling connects with the broader idea of remaining reliable, balanced, or unchanged.
In context
stable region in that system and here are the perturbation maps in this case green means no perturbation or almost no perturbation for the type 2 it will not change energy
More examples
- Food prices remain stable despite rising fuel costs.
- Her condition is stable, but she still needs hospital care.
- A stable income makes it easier to plan ahead.