Bilge is the lowest part inside a ship's hull, where the curved bottom meets the sides. Water naturally collects there: rainwater dripping through hatches, seawater seeping through tiny gaps, condensation from temperature changes, or spray from rough seas.

This pooled water is called bilge water, and it can cause serious problems if it builds up. Too much bilge water makes a ship unstable and harder to steer. It can also start to smell terrible and damage the ship's structure. That's why ships have bilge pumps that automatically remove this water and pump it overboard.

On small sailboats, you might see someone bail out the bilge with a bucket or sponge. On large ships, electric pumps run constantly, keeping the bilge dry. Naval inspections always check the bilge because a clean, dry bilge indicates a well-maintained ship.

The word can also mean nonsense or foolish talk. When someone says “That's bilge!” they mean it's ridiculous or untrue, like the foul-smelling water nobody wants in their boat. You might hear someone dismiss a wild excuse as “complete bilge.”