apheresis vs omission

apheresis

noun
  • Elision, suppression, or complete loss of a letter or sound (syllable) from the beginning of a word, such as the development of special from especial; procope. 

  • The removal of blood from a patient, and the removal of certain components (such as platelets) from that blood, followed by the transfusion of the filtered blood back to the donor (patient). 

omission

noun
  • The shortening of a word or phrase, using an apostrophe ( ' ) to replace the missing letters, often used to approximate the sound of speech or a specific dialect. 

  • Something not done or neglected. 

  • An instance of those acts, or the thing left out thereby; something deleted or left out. 

  • The act of neglecting to perform an action one has an obligation to do. 

  • The act of omitting. 

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