slippery

Short definition from Wiktionary

Adjective

1. 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.
2. 2
   Evasive; difficult to pin down.
3. 3
   Liable to slip; not standing firm.
4. 4
   Unstable; changeable; inconstant.
5. 5
   Wanton; unchaste; loose in morals.