frow vs placket

frow

noun
  • A cleaving tool with handle at right angles to the blade, for splitting cask staves and shingles from the block; a frower. 

  • A woman; a wife, especially a Dutch or German one. 

adj
  • Brittle; tender; crisp 

placket

noun
  • An additional plate of steel on the lower half of the breastplate or backplate. 

  • A leather jacket strengthened with strips of steel. 

  • A slit or other opening in an item of clothing, to allow access to pockets or fastenings 

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