Source : Webster's Revised Unabridged Dictionary (1913)

Soapwort \Soap"wort`\, n. (Bot.)
   A common plant ({Saponaria officinalis}) of the Pink family;
   -- so called because its bruised leaves, when agitated in
   water, produce a lather like that from soap. Called also
   {Bouncing Bet}.

Source : WordNet®

soapwort
     n : plant of European origin having pink or white flowers and
         leaves yielding a detergent when bruised [syn: {hedge
         pink}, {bouncing Bet}, {bouncing Bess}, {Saponaria
         officinalis}]