'bilge' originates from Middle English, specifically the word 'bilge,' which is believed to be related to Old Norse 'bylgja' where the root meant 'swell' or 'wave'.

'bilge' developed from Old Norse forms (related to 'bylgja') into Middle English 'bilge' and eventually the modern English word 'bilge', shifting from a general sense of 'swelling' to the specific part of a ship and related senses.

Initially it referred to a swelling or bulge (a rounded or swollen part). Over time it became specialized to mean the swollen/bottom part of a ship and the water that accumulates there; later it acquired a figurative sense of 'nonsense' or 'worthless stuff'.