double over vs incurvate

double over

verb
  • To bend over at the waist. 

incurvate

verb
  • To bend (especially inwards); to give a curved shape to. 

  • to have a curved or bent shape; to bend or curve inwards. 

adj
  • bending inwards. 

  • Curved; bent; crooked. 

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