clag vs dirt

clag

verb
  • To stick, like boots in mud 

noun
  • Unburned carbon (smoke) from a steam or diesel locomotive, or multiple unit. 

  • Bits of rubber which are shed from tires during a race and collect off the racing line, especially on the outside of corners (cf. marbles). 

  • A glue or paste made from starch. 

  • Low cloud, fog or smog. 

dirt

verb
  • To make foul or filthy; soil; befoul; dirty 

noun
  • A stain or spot (on clothes etc); any foreign substance that worsens appearance. 

  • Previously unknown facts, or the invented "facts", about a person. 

  • Meanness; sordidness. 

  • In placer mining, earth, gravel, etc., before washing. 

  • freckles 

  • Soil or earth. 

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