To slicken means to make something smooth and shiny, usually by rubbing it.
Slicken can make people think of cleaning, making things look nice, or of being careful.
Examples:
She used a cloth to slicken the table.
I slicken my shoes before going out.
The rain slickened the road, making it dangerous to drive.
I slicken the floor so I can slide around!
He slickened the sword until it shone like the sun.
The magician slickened the coin before making it disappear.