rafter vs strengthener

rafter

verb
  • To furnish (a building) with rafters. 

  • To make (timber, etc.) into rafters. 

  • To plough so as to turn the grass side of each furrow upon an unploughed ridge; to ridge. 

noun
  • A raftsman. 

  • A flock of turkeys. 

  • One of a series of sloped beams that extend from the ridge or hip to the downslope perimeter or eave, designed to support the roof deck and its associated loads. 

strengthener

noun
  • One who, or that which, gives or adds strength. 

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