dilation vs diminution

dilation

noun
  • In morphology, a basic operation (denoted ⊕) that usually uses a structuring element for probing and expanding the shapes contained in the input image. 

  • State of being dilated; expansion; dilatation. 

  • The act of dilating. 

diminution

noun
  • A lessening, decrease or reduction. 

  • a compositional technique where the composer shortens the melody by shortening its note values. 

  • The act or process of making diminutive. 

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