#boulder__bowlder  a large smooth mass of rock detached from its place of origin
  supertype:  rock.natural_object__stone  a lump of hard consolidated mineral matter; "he threw a rock at me"
  instance:  Plymouth_Rock.boulder
  subtype:  glacial_boulder__glacialboulder  a boulder that has been carried by a glacier to a place far distant from its place of origin
  subtype:  river_boulder__riverboulder  a boulder that has been carried by a river to a place remote from its place of origin
  subtype:  shore_boulder__shoreboulder  a boulder found on a shore remote from its place of origin

No statement uses or specializes boulder; click here to add one.