If you mean "steady and not likely to change":
* Stable (adjective) - This is the most direct adjective.
* Steady (adjective) - This implies a consistency over time.
* Firm (adjective) - This implies a strength and solidity.
* Solid (adjective) - This emphasizes a lack of movement or change.
* Secure (adjective) - This implies a feeling of safety and confidence.
If you mean "relating to a stable for horses":
* Equine (adjective) - This refers to horses in general.
* Stalled (adjective) - This refers to being kept in a stable.
Example:
* "The company's financial situation is stable." (steady and not likely to change)
* "She has a steady job." (consistent over time)
* "The horse is kept in a stable." (relating to a stable for horses)
The best adjective to use will depend on the specific meaning you want to convey.