low tide vs undertow

low tide

noun
  • The time of day when the sea has receded to its lowest level. 

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

undertow

noun
  • A short-range flow of water returning seaward from the waves breaking on the shore. 

  • A feeling that runs contrary to one's normal one. 

verb
  • To pull down by, or as by, an undertow. 

  • To flow or behave as an undertow. 

  • To pull or tow under; drag beneath; pull down. 

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