high tide vs highwater

high tide

noun
  • The time of day when the sea has risen to its highest level. 

  • Synonym of menstruation 

  • The natural tide at its highest level for a particular tidal cycle at a certain place. 

  • climax, culminating point or phase 

highwater

noun
  • Synonym of high water 

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