The Collaborative International Dictionary of English v.0.48:

Pilewort \Pile"wort`\, n. (Bot.)
   A plant (Ranunculus Ficaria of Linn[ae]us) whose tuberous
   roots have been used in poultices as a specific for the
   piles. --Forsyth.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pilewort
    n 1: perennial herb native to Europe but naturalized elsewhere
         having heart-shaped leaves and yellow flowers resembling
         buttercups; its tuberous roots have been used as a poultice
         to relieve piles [syn: lesser celandine, pilewort,
         Ranunculus ficaria]