Citron
The citron ("Citrus medica") is a large fragrant citrus fruit with a thick rind. It is one of the original citrus fruits from which all other citrus types developed through natural hybrid speciation or artificial hybridization. Though citron cultivars take on a wide variety of physical forms, they are all closely related genetically. It is used widely in Asian cuisine, and also in traditional medicines, perfume, and for religious rituals and offerings. Hybrids of citrons with other citrus are commercially prominent, notably lemons and many limes.
Limey
The term is thought to have originated in the 1850s as "lime-juicer", later shortened to "limey", and originally used as a derogatory word for sailors in the British Royal Navy. Since the beginning of the 19th century it had been the practice of the Royal Navy to add lemon juice to the sailors' daily ration of grog (watered-down rum). The vitamin C (specifically acid) in citrus fruits prevented scurvy , and helped to make these sailors some of the healthiest of the time. At that time "lemon" and "lime" were used interchangeably to refer to citrus fruits. Initially, lemon juice (from lemons imported from Europe) was used as the additive to grog on the Royal Navy ships, but was later switched to limes (grown in British colonies), not realizing that limes did not contain sufficient Vitamin C to prevent the disease.