SLIPPERIEST

Of a surface, having low friction, often due to being covered in a non-viscous liquid, and therefore hard to grip, hard to stand on without falling, etc.

Example: "Oily substances render things slippery."

(by extension) evasive; difficult to pin down.

Example: "A slippery person"

Liable to slip; not standing firm.

Unstable; changeable; inconstant.

Wanton; unchaste; loose in morals.