slippery

American Heritage® Dictionary of the English Language, Fourth Edition

1. adj. Causing or tending to cause sliding or slipping: a slippery sidewalk.
2. adj. Tending to slip, as from one's grasp: a slippery bar of soap.
3. adj. Not trustworthy; elusive or tricky: "How extraordinarily slippery a liar the camera is” ( James Agee).

Century Dictionary and Cyclopedia

1. Having such smoothness of surface as to cause slipping or sliding, or to render grip or hold difficult; not affording firm footing or secure hold.
2. Hence That cannot be depended on or trusted; uncertain; untrustworthy; apt to play one false; dishonest: as, he is a slippery person to deal with; slippery politicians.
3. Liable to slip or lose footing.
4. Unstable; changeable; mutable.
5. Lubric; wanton; unchaste.
6. Crafty; sly.

Wiktionary

1. adj. 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. adj. figuratively, by extension Evasive; difficult to pin down.
3. adj. obsolete Liable to slip; not standing firm.
4. adj. unstable; changeable; inconstant
5. adj. obsolete wanton; unchaste; loose in morals

GNU Webster's 1913

1. adj. Having the quality opposite to adhesiveness; allowing or causing anything to slip or move smoothly, rapidly, and easily upon the surface; smooth; glib.
2. adj. Not affording firm ground for confidence.
3. adj. Not easily held; liable or apt to slip away.
4. adj. Liable to slip; not standing firm.
5. adj. Unstable; changeable; mutable; uncertain; inconstant; fickle.
6. adj. Uncertain in effect.
7. adj. Wanton; unchaste; loose in morals.

WordNet 3.0

1. adj. not to be trusted
2. adj. causing or tending to cause things to slip or slide