aphesis vs syncopation

aphesis

noun
  • The loss of the initial unstressed vowel of a word. 

syncopation

noun
  • The contraction of a word by means of loss or omission of sounds or syllables in the middle thereof. 

  • The quality of a rhythm being somehow unexpected, in that it deviates from the strict succession of regularly spaced strong and weak beats in a meter. 

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