mere vs plunge pool

mere

noun
  • A body of standing water, such as a lake or a pond. More specifically, it can refer to a lake that is broad in relation to its depth. Also included in place names such as Windermere. 

  • A Maori war-club. 

  • Boundary, limit; a boundary-marker; boundary-line. 

adj
  • Just, only; no more than, pure and simple, neither more nor better than might be expected. 

verb
  • To decide upon the position of a boundary; to position it on a map. 

plunge pool

noun
  • A pool that is small in diameter, but deep, usually resulting from erosion by a natural force such as a waterfall or rapids. 

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