clustering vs intensification

clustering

noun
  • The undesirable contiguous grouping of elements in a hash table. 

  • A grouping of a number of similar things. 

  • A prewriting technique consisting of writing ideas down on a sheet of paper around a central idea within a circle, with the related ideas radially joined to the circle using rays. 

  • The grouping of a population based on ethnicity, economics or religion. 

adj
  • Forming a cluster. 

intensification

noun
  • The act or process of intensifying, or of making more intense. 

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