bellyacher(n = noun.person) complainer, crybaby, grumbler, moaner, sniveller, squawker, whiner - a person given to excessive complaints and crying and whining;
is a kind of disagreeable person, unpleasant person
has particulars: kvetch
Derived form verb bellyache1
a person who complains habitually, usually about everyday minor problems. [WordNet 1.5]