ebb and flow vs ebb tide

ebb and flow

noun

  • The flowing out and in of the tide. 

  • A large flowing out and in. 

verb

  • To alternately ebb and flow. 

ebb tide

noun

  • The period between high tide and the next low tide in which the sea is receding. 

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