The term 'Navel Base' can be broken down into three crossword solutions: BELLY (5 letters), ORANGE (6 letters), and Orangetree (10 letters). The term 'Navel Base' is a type of ORANGE that was developed in the 1970s at the Riverside, California, campus of the University of California. It is a seedless variety of ORANGE that has a distinctive navel-like shape at the stem end. The ORANGE is known for its sweet flavor and is widely grown in California, Arizona, and Florida.