best friend vs intimate

best friend

noun
  • An especially close and trusted friend. 

  • Used other than figuratively or idiomatically: see best, friend. 

  • An object or concept considered very useful or helpful. 

intimate

noun
  • A very close friend. 

  • Women's underwear, sleepwear, or lingerie, especially offered for sale in a store. 

verb
  • To suggest or disclose (something) discreetly. 

  • To notify. 

adj
  • Pertaining to details that require great familiarity to know. 

  • Closely acquainted; familiar. 

  • Very finely mixed. 

  • Of or involved in a sexual relationship. 

  • Personal; private. 

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