neither vs otherwise

neither

adv
  • Similarly not. 

det
  • Not one of two; not either. 

  • Not either (used with nor). 

pron
  • Not either one of two. 

otherwise

adv
  • Differently, in another way. 

  • In different circumstances; or else. 

  • In all other respects. 

adj
  • Other than supposed; different. 

How often have the words neither and otherwise occurred in a corpus of books? (source: Google Ngram Viewer )