The term "bilge" has several meanings, depending on its context.
In general usage, it refers to water that collects in the lowest part of a ship or boat, especially when it is not properly draining. This accumulated water is known as bilge water and can cause damage if left unattended.
However, "bilge" can also refer to the lowest compartment on a ship where this water collects, which is often located at the bottom of the hull. In this context, it refers to the entire area that collects water rather than just the water itself.
Finally, in some nautical terminology, "bilge" can refer to the lowest point or level on a ship - as in "the bilge of the boat." This usage is more specific and technical, referring to the lowest part of the hull where water collects rather than the actual accumulated water.