Meyer lemon, known botanically as Citrus x meyeri, is a hybrid of a citron and a mandarin/pomelo hybrid. They are prized in cooking because of their generous, sweet juice, which is less acidic than a true lemon.
Meyer lemons were developed in China, where they are known as 香柠檬, "xiangningmeng." They were introduced to the United States in 1908 by Frank Nicholas Meyer, from whom they take their English name.