• (n.) A cement made in India from sea shells, pulverized and mixed with oil, and spread over a ship`s bottom, to prevent the boring of worms.
Gul'gul noun [ Hind. galgal .] A cement made in India from sea shells, pulverized and mixed with oil, and spread over a ship's bottom, to prevent the boring of worms. 
a preparation of pulverized seashells and oil, applied to the wooden hull of a ship as a protection against boring worms.