3. Stagnant
(of a body of water or the
atmosphere of a confined space)
Having no current or flow and often
having an unpleasant smell as a
consequence.
Showing no activity; dull and
sluggish: "a stagnant economy".
4. Precarious
Not securely held or in position;
dangerously likely to fall or collapse.
Dependent on chance; uncertain
5. impregnable
(of a fortified position) Unable to be
captured or broken into: "an
impregnable wall of solid sandstone";
"impregnable to takeovers".
Unable to be defeated or destroyed;
unassailable