The Collaborative International Dictionary of English v.0.48:

Pellagra \Pel"la*gra\ (p[e^]l"l[.a]*gr[.a]), n. [It. pelle skin
   + agro rough.] (Med.)
   An affection of the skin, characterized by redness,
   especially in exposed areas, scaling and shedding of the
   skin, and accompanied with severe gastrointestinal
   disturbance and nervous symptoms. It is due to a deficiency
   of niacin (vitamin B3; nicotinic acid) and protein in the
   diet, and may be caused by malnutrition, or, in some cases,
   by a heavy dependence on maize for food. It was at one time
   (ca. 1890) endemic in Northern Italy, and was called Alpine
   scurvy. It may also be caused by alcoholism or diease
   causing an impairment of nutrition. It is also called St.
   Ignatius's itch, maidism, mal de la rosa, mal rosso,
   and psychoneurosis maidica. A variety of pellagra seen in
   children is called infantile pellagra or kwashiorkor.
   --[Stedman]
   [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

kwashiorkor
    n 1: severe malnutrition in children resulting from a diet
         excessively high in carbohydrates and low in protein