1.  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;
is a kind of citrus, citrus tree
has parts: kumquat
is a member of fortunella, genus fortunella
has particulars: fortunella japonica, marumi, marumi kumquat, round kumquat, fortunella margarita, nagami, nagami kumquat, oval kumquat

2.  kumquat(n = noun.food) - small oval citrus fruit with thin sweet rind and very acid pulp;
is a kind of citrous fruit, citrus, citrus fruit
is a part of cumquat, kumquat, kumquat tree

   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.

Etymology:
Cantonese var. of Chin. kin k{uuml} golden orange

kumquat tree, marumi kumquat, nagami kumquat, oval kumquat, round kumquat