1. Of a liquid or gas, to enter into something or some place in a great gush or burst. Cold air comes surging in the house if you leave the doors open for more than a couple of seconds. Rainwater started surging in through a crack in the window.

2. Of people, animals, or things, to enter something or some place in large numbers and all at once. Hundreds of people surged in the store to nab one of their amazing Black Friday deals. A huge colony of bats surged in the air from the mouth of the cave.

3. To quickly or suddenly gain a very large amount of something. The TV show had a bit of a slow start, but surged in popularity during its second season. The product has been surging in sales after receiving recommendations from high-profile doctors as a safe and effective weight-loss supplement.

4. To become much greater, larger, or more numerous in some particular setting or context. Credit card debt surged in the late 2000s as people were given higher limits and more time to pay back their lenders. Raw sewage began surging in the basement from a burst pipe.

5. To quickly or suddenly move ahead in position or popularity in a political election. The decorated war veteran has surged in the race for her party's nomination following her impressive performance in the primary debate. Despite what some thought was damning evidence, the candidate has nonetheless been surging in the polls lately.