drill bit vs drilling

drill bit

noun
  • A twist drill. 

  • Any other style of cutter, for example a spade drill, that is rotated and fed in a similar manner as a twist drill to of cut a hole in metal, wood or other materials. 

drilling

noun
  • Act of drilling. 

  • A heavy, twilled fabric of linen or cotton; drill. 

  • A long firearm with three barrels (typically a mix of shotgun and rifle barrels). 

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