difficult to hold or to stand or move on, because it is smooth, wet or polished
slippery like a fish
In places the path can be wet and slippery.
His hand was slippery with sweat.
of a person
that you cannot trust
Don't believe what he says─he's a slippery customer.
of a situation, subject, problem, etc.
difficult to deal with and that you have to think about carefully
Freedom is a slippery concept (= because its meaning changes according to your point of view) .
a course of action that is difficult to stop once it has begun, and can lead to serious problems or disaster