undertone vs vibe

undertone

noun
  • An auditory tone of low pitch or volume. 

  • A pale colour, or one seen underneath another colour. 

  • A low state of the physical faculties. 

  • An implicit message perceived subtly alongside, but not detracting noticeably from, the explicit message conveyed in or by a book, film, verbal dialogue or similar (contrast with overtone); an undercurrent. 

verb
  • To accompany as an undertone. 

  • To say or speak in an undertone. 

  • To present as less important, noticeable or prominent. 

vibe

noun
  • Vibration. 

  • An atmosphere or aura felt to belong to a person, place or thing. 

  • A vibrator (sex toy). 

  • A vibraphone. 

verb
  • To agree. 

  • To get along; to hit it off. 

  • To relax and enjoy oneself. 

  • To feel in agreement with; to appreciate. 

  • To stimulate with a vibrator. 

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