building block vs clunch

building block

noun
  • A component that is part of a larger construction, such as a brick or a stone. 

  • A block made of wood or plastic that is used as a children's toy and can be stacked or joined to form a larger structure. 

  • A component that is part of a larger system. 

clunch

noun
  • A traditional building material mostly made of chalk or clay. 

verb
  • To grasp firmly; clench. 

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