Slipperier

adjective

1. 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.

   "Oily substances render things slippery."

2. (by extension) Evasive; difficult to pin down.

   "a slippery person"

3. Liable to slip; not standing firm.
4. Unstable; changeable; inconstant.
5. Wanton; unchaste; loose in morals.