Lime juice: The British Royal Navy began issuing daily rations of lime juice to sailors in the 18th century to prevent scurvy, a disease caused by a deficiency of vitamin C. Sailors who regularly consumed lime juice were healthier and had fewer cases of scurvy compared to their counterparts in other navies. This led to the association between British sailors and the consumption of lime juice, and the term "limey" became a nickname for them.
Lime-washed decks: Another possible origin of the term lies in the practice of washing the decks of British ships with a mixture of water, sand, and lime. This process, known as "limewashing," was used to clean and whiten the decks. The lime residue left on the decks could have contributed to the nickname "limey" for British sailors.
Limescale: In hard water areas, limescale can form on surfaces due to the presence of calcium and magnesium ions. It was observed that British ships, particularly those that spent long periods at sea, often had limescale deposits on their decks, hulls, and other metal surfaces. This association could have led to the term "limey" being applied to British sailors.
It's worth noting that the use of the term "limey" is considered offensive and derogatory in some contexts, and it is generally avoided in polite discourse.