DuckCorp Dico

Found one definition

1.                 From WordNet (r) 3.0 (2006):
                   
   
   
                   
                     
   nodule
       n 1: a small node
       2: small rounded wartlike protuberance on a plant [syn:
          nodule, tubercle]
       3: (mineralogy) a small rounded lump of mineral substance
          (usually harder than the surrounding rock or sediment)