Firm and not likely to fail; stable.
Free from the danger of theft; safe.
Certain to be achieved or gained; assured.
Free from attack or danger; protected.
Free from the risk of eavesdropping, interception or discovery; secret.
Confident in opinion; not entertaining, or not having reason to entertain, doubt; certain; sure; commonly used with of.
Free from anxiety or doubt; unafraid.
Free from the risk of financial loss; reliable.
To make fast; to close or confine effectually; to render incapable of getting loose or escaping.
To get possession of; to make oneself secure of; to acquire certainly.
To make safe; to relieve from apprehensions of, or exposure to, danger; to guard; to protect.
To put beyond hazard of losing or of not receiving; to make certain; to assure; frequently with against or from, or formerly with of.
Not stable.
Readily decomposable.
Radioactive, especially with a short half-life.
Unpredictable.
Fickle.
Having a strong tendency to change.
Fluctuating; not constant.
To release (an animal) from a stable.