previous vs sometime

previous

adj
  • Prior; occurring before something else, either in time or order. 

  • Premature; acting or occurring too soon. 

noun
  • An existing criminal record (short for "previous convictions") 

  • A track record of similar behaviour. 

sometime

adj
  • Former, erstwhile; at some previous time. 

  • Occasional. 

adv
  • At an indefinite but stated time in the past or future. 

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