v.1. To inflate something with gas by using a pump: We pumped up a new basketball before the game. One of my tires was getting low, so I stopped at a gas station and pumped it up.
2. To force or suck something, as a liquid or gas, from beneath a surface by using a pump: This well pumps up oil from underground. We pump the water up from the lake to tanks on the hillside.
3. Slang To fill someone with enthusiasm, strength, and energy; psych someone up: The crowd's chants pumped up the players. The coach pumped us up for the big game with a rousing speech.
4. Slang To be actively involved in bodybuilding exercises: The football players are always pumping up at the gym.
5. Slang To strengthen something: Pump up the volume on that stereo—I can't hear it. The economy was declining, but investors hoped that a favorable exchange rate would pump it up.