lubricating oil

smooth; oily; sleek; to lubricate

lubricant

to polish (a piece of writing); to add a few finishing touches to (a piece of writing, painting etc)

(neologism) (slang) study of how to flee from adverse conditions in China by emigrating

profits

moist

moist; humid; to moisten; to provide moisture; comfortably off

glossy; lustrous; sleek

mellow and full; suave; smooth and round; rich (in voice)