accessary vs occasional

accessary

adj
  • Accompanying as a subordinate; additional; accessory; especially, uniting in, or contributing to, a crime, but not as chief actor. See accessory. 

noun
  • Someone who accedes to some act, now especially a crime; one who contributes as an assistant or instigator to the commission of an offense. 

occasional

adj
  • Acting in the indicated role from time to time. 

  • Created for a specific occasion. 

  • Occurring or appearing irregularly from time to time, but not often. 

  • Intended for use as the occasion requires. 

noun
  • A person who does something only occasionally. 

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