1. To force a liquid or gas into someone or something through the use of a pump. They've been pumping oxygen into him to keep him alive. You need to use the primer on the lawn mower to pump gasoline into the carburetor before the engine will start.

2. To provide large amounts of money to something, such as a company, project, or business venture. The billionaire has been pumping millions of dollars into space exploration research. We've pumped too much money in this business as it is—it's time to cut our losses and call it quits.