lethal vs strengthening

lethal

adj
  • Of, pertaining to, or causing death; deadly; mortal; fatal. 

noun
  • One of the higher alcohols of the paraffine series obtained from spermaceti as a white crystalline solid. 

  • An allele that causes the death of the organism that carries it. 

  • Any weapon that causes death. 

strengthening

noun
  • The process by which something is strengthened. 

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