quiver vs somersault

quiver

verb
  • To shake or move with slight and tremulous motion. 

noun
  • A multidigraph. 

  • A ready storage location for figurative tools or weapons. 

  • A container for arrows, crossbow bolts or darts, such as those fired from a bow, crossbow or blowgun. 

somersault

verb
  • To perform a somersault. 

noun
  • Starting on one's feet, an instance of rotating one's body 360 degree while airborne or on the ground, with one's feet passing over one's head. 

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