kumquat(n = noun.plant) cumquat, kumquat tree - any of several trees or shrubs of the genus Fortunella bearing small orange-colored edible fruits with thick sweet-flavored skin and sour pulp;
any of several trees or shrubs of the genus Fortunella (formerly Citrus) of the rue family (Rutaceae) (especially Citrus Japonica) growing in China and Japan bearing small orange-colored edible fruits with thick sweet-flavored skin and sour pulp; also, any of the small acid, orange-colored citrus fruits of such plants, used mostly for preserves. [1913 Webster]
Kumquat, n. (also cumquat)
1 an orange-like fruit with a sweet rind and acid pulp, used in preserves.
2 any shrub or small tree of the genus Fortunella yielding this.