let go vs put down

let go

verb
  • Used other than figuratively or idiomatically: see let, go. 

  • To dismiss from employment. 

  • To release from one's grasp; to go from a state of holding on to a state of no longer holding on. 

  • To ignore (a comment, etc.). 

  • To emotionally disengage or to distract oneself from a situation. 

  • To fail to maintain a standard of appearance, behavior, or performance. 

  • To gain weight 

put down

verb
  • Used other than figuratively or idiomatically: see put, down. 

  • To drop someone off, or let them out of a vehicle. 

  • To euthanize (an animal). 

  • To make prices, or taxes, lower. 

  • To pay. 

  • To terminate a call; to hang up. 

  • To give something as a reason for something else. 

  • To add a name to a list. 

  • To insult, belittle, or demean. 

  • To halt, eliminate, stop, or squelch, often by force. 

  • To land. 

  • To execute (a person), especially extrajudicially. 

  • To write (something). 

  • To place a baby somewhere to sleep. 

  • To cease, temporarily or permanently, reading (a book). 

How often have the words let go and put down occurred in a corpus of books? (source: Google Ngram Viewer )