Well, that would be the question of the day, wouldn't it? if you want the literal definition, check out this bit of insight from The Food Lover's Companion, 2nd edition, by Sharon Tyler Herbst, Barron's Educational Services, Inc.
kumquat [KUHM-kwaht] This pigmy of the citrus family looks like a tiny oval or round orange. It's cultivated in China, Japan and the United States. The edible golden orange rind is sweet, while the rather dry flesh is very tart. The entire fruit - skin and flesh - is eaten, and very ripe fruit can be sliced and served raw in salads or as a garnish. The kumquat is more likely to be found cooked, however, either candied or pickled whole or in preserves or marmalades. Fresh kumquats are available from November to March. Look for firm fruit without blemishes. Refrigerate wrapped in a plastic bag for up to a month. Kumquats contain good amounts of potassium and vitamins A and C.