Sentence:  America's poverty line is $63 a day for a family of four. In the richer <WSD>parts</WSD> of the emerging world $4 a day is the poverty barrier. But poverty's scourge is fiercest below $1.25 ([...]): people below that level live lives that are poor, nasty, brutish and short. 
Meaning of the word marked with <WSD> tags:  A fraction of a whole. (t)