1. Regarding a person or something impervious to change; unvarying; steady; not subject to insecurity: Sally was stable in her commitment to pursue her career goals.

Linda's mental health was now stable and she was encouraged to go back to work.
2. Referring to something which is not reacting chemically: The mixture in the test tube is stable and will not change when water is added.
3. Pertaining to something which is fastened, secure, and safe: Once the crew had snugged the barrels on the deck, they were stable and would not roll around in the storm.
4. Concerning a person who is well-balanced, sensible, and reasonable: Judy seemed to be very reliable, unwavering, and a stable individual and was chosen to be secretary in the committee on saving the environment.