#firth  a long narrow estuary (especially in Scotland)
  supertype:  #estuary  the wide part of a river where it nears the sea; fresh and salt water mix
  subtype:  #Firth_of_Forth  a large firth on the east coast of Scotland; location of Edinburgh
  subtype:  #Solway_Firth  a large firth on the west coast of Britain between England and Scotland

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