If something is slicked, it means it has been made smooth and shiny, usually by putting a wet or oily substance on it.
Slicked things can be slippery and look very neat and clean.
Examples:
He slicked back his hair with gel.
The road was slicked with rain.
The cat's fur was slicked down by the rain.
She slicked the floor with oil and slid around.
The car was so slicked that it shone like the sun.
The dog slicked its fur with water and looked very neat.