sta·ble 1 
(stābəl)
(stābəl)adj. sta·bler, sta·blest
1.
a. Resistant to change of position or condition; not easily moved or disturbed: a house built on stable ground; a stable platform.
b. Not subject to sudden or extreme change or fluctuation: a stable economy; a stable currency.
c. Maintaining equilibrium; self-restoring: a stable aircraft.
2. Enduring or permanent: a stable peace.
3.
a. Consistent or dependable: She has been stable in her support for the project.
b. Not showing or marked by erratic or volatile emotions or behavior: He remained stable even after he lost his job.
4. Physics Having no known mode of decay; indefinitely long-lived. Used of atomic particles.
5. Chemistry Not easily decomposed or otherwise modified chemically.
[Middle English, from Old French estable, from Latin stabilis; see stā- in the Appendix of Indo-European roots.]
stable·ness n.
stably adv.