Something is slippery if it very hard to get a hold of, or you can't stick to it. A slippery surface is one your shoes or feet don't grip onto, so you fall over when you are walking on them. Slippery things are usually very smooth and are often wet and slimey. Some things that are slippery are ice, wet roads, banana peels, and rocks at the beach at low tide that have algae growing on them. The opposite of slippery is sticky.