A surge is a sudden, powerful forward movement or increase. When ocean waves surge toward the shore during a storm, they rush in with tremendous force. When a crowd surges forward at a concert, everyone pushes ahead at once. When electricity surges through power lines, it spikes dangerously high.

The word captures that sense of powerful momentum: not a gentle rise but a forceful rush. A hospital might experience a surge of patients during flu season, meaning many more people arrive than usual, all at once. A runner might feel a surge of energy in the final stretch of a race. A company's stock price might surge after good news.

You can also use surge as a verb: crowds surge, rivers surge over their banks, and your confidence might surge when you finally understand a difficult concept.

The word often implies something difficult to control. A power surge can damage electronics because the sudden spike in electricity is too much for devices to handle safely. A storm surge pushes seawater inland during hurricanes, flooding coastal areas. Whether it's water, electricity, emotion, or people, a surge means a sudden, powerful rush that's hard to stop once it starts.