There are two accounts explaining the etymology of the name Jeddah, which is pronounced Jiddah in Arabic. According to the less common account, it means "seashore," since Jeddah is located along the coast and is Saudi Arabia's most important port. Some people, however, prefer to pronounce it Jaddah, which means "grandmother": in Islamic tradition, the tomb of Eve, grandmother of all humanity, is located in the city. The supposed tomb was concreted-over by the authorities in 1975, as some uneducated Moslem pilgrims were praying to Eve there, which is strictly against the Moslem religion.
The British Foreign Office still insists on using the older spelling of Jedda, contrary to all other English-speaking usage - including other branches of the British government.