Seepage is the slow, gradual movement of liquid through small openings or porous materials. Water might show seepage through cracks in a basement wall after heavy rain, appearing as damp spots that grow larger over time. Oil can create seepage through the ground, leaving dark patches on the surface.

The word describes something that oozes or trickles rather than pours. A dam might develop seepage where water finds tiny gaps in the concrete and slowly works its way through. Underground water creates seepage that feeds springs and keeps soil moist. Unlike a sudden flood or spray, seepage happens so slowly you might not notice it at first, but over time it can cause real problems, like weakening foundations or creating puddles where you don't want them.

The verb form is seep: “Water began to seep through the tent during the storm.” Seepage can happen with any liquid: gasoline seeping from an old tank, juice seeping through a paper bag, or groundwater seeping up through packed dirt. The key idea is that slow, persistent movement through materials that aren't completely watertight.