caveat vs mayday

caveat

noun
  • A warning. 

  • A formal objection. 

  • A notice requesting a postponement of a court proceeding. 

  • A qualification or exemption. 

  • A formal notice of interest in land under a Torrens land-title system. 

verb
  • To formally object to something. 

  • To qualify a statement with a caveat or proviso. 

  • To lodge a formal notice of interest in land under a Torrens land-title system. 

mayday

noun
  • An international distress signal used by shipping and aircraft. 

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