|Origin:||slipper 'slippery' (11-19 centuries), from Old English slipor|
something that is slippery is difficult to hold, walk on etc because it is wet or greasy:
In places, the path can be wet and slippery.
Harry's palms were slippery with sweat.
someone who is slippery cannot be trusted:
Martin is a slippery customer (=someone you should not trust) so be careful what you say to him.
not having one clear meaning and able to be understood in different ways:
the slippery notion of 'standards'
4 British English informal
used to talk about a process or habit that is difficult to stop and which will develop into something extremely bad
(be on) a/the slippery slope to/towards
He is on the slippery slope to a life in crime.
—slipperiness noun [uncountable]