estuary vs frith

estuary

noun
  • A coastal water body where ocean tides and river water merge, resulting in a brackish water zone. 

  • An ocean inlet also fed by fresh river water. 

frith

noun
  • Brushwood or undergrowth, sometimes in the form of a hedge. 

  • A forest or wood; woodland generally. 

  • Land with mostly undergrowth and few trees; also, land in between forests or woods; pastureland which is not in use. 

  • A hedge, especially one made from brushwood which has been wattled; also, a movable frame made from wattled branches, a hurdle. 

How often have the words estuary and frith occurred in a corpus of books? (source: Google Ngram Viewer )