lasting vs unsystematic

lasting

noun
  • A durable woollen material formerly used for women's shoes. 

  • The act or process of shaping footwear on a last. 

adj
  • Persisting for an extended period of time. 

unsystematic

adj
  • Not systematic 

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