bygone vs perfective aspect

bygone

noun
  • An event that happened in the past. 

adj
  • Having been or happened in the distant past. 

perfective aspect

noun
  • A feature of the verb which denotes viewing the event the verb describes as a completed whole, rather than from within the event as it unfolds. For example, "she sat down" as opposed to "she was sitting down". Since the focus is on the completion of what is expressed by the verb, this aspect is generally associated with the past and future tenses. This term is often used interchangeably with aorist aspect. This is not to be confused with the perfect tense. 

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