To apply a lubricant, such as oil or grease, to a surface or mechanism to reduce friction and ensure smooth operation. He greased the bicycle chain to make the ride smoother.
To bribe or offer an illicit payment to someone in order to gain favor or expedite a process. She had to grease the official's palm to get the paperwork processed quickly.
To make something slippery or smooth by applying grease or a similar substance. The cook greased the baking pan before pouring in the batter.
(slang) To kill or murder, especially with a firearm. The mob boss ordered his men to grease anyone who talked.