Sentence:  But poverty's scourge is fiercest below $1.25 (the average of the 15 poorest countries' own poverty lines, measured in 2005 <WSD>dollars</WSD> and adjusted for differences in purchasing power): people below that level live lives that are poor, nasty, brutish and short. 
Meaning of the word marked with <WSD> tags:  A quarter of a pound or one crown, historically minted as a coin of approximately the same size and composition as a then-contemporary dollar coin of the United States, and worth slightly more.