The largest citrus fruit is the POMELO, which has 6 letters. It is a large, round citrus fruit that is native to Southeast Asia and is related to the grapefruit. It has a thick, yellow-green rind and a sweet, juicy flesh. The POMELO is the largest of all citrus fruits, with some varieties weighing up to 10 pounds. It is also known for its high vitamin C content and is often used in salads, juices, and desserts.