diver vs shipmate

diver

noun
  • Someone who works underwater; a frogman. 

  • Someone who dives, especially as a sport. 

  • The New Zealand sand diver. 

  • A competitor in certain sports who is known to regularly imitate being fouled, with the purpose of getting his/her opponent penalised. 

  • The long-finned sand diver. 

  • loon (bird) 

shipmate

noun
  • A fellow sailor serving on the same ship as another. 

  • Any sailor (when used as a form of address by a sailor). 

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