From HomoExcelsior

1. Resistant to change of position or condition; steadfast. 2. Maintaining equilibrium; self-restoring. 3. Immutable; permanent; enduring. 4. Consistently dependable. 5. Not subject to mental illness or irrationality. 6. Having no known mode of decay; indefinitely long-lived. Used of atomic particles. 7. Not easily decomposed or otherwise modified chemically.

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