let go vs romp

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 

romp

verb
  • (Often used with down) To press forcefully, to encourage vehemently, to oppress. 

  • To play about roughly, energetically or boisterously. 

  • To engage in playful or boisterous sex. 

  • To win easily. 

  • To move with little effort relatively quickly. 

noun
  • An enjoyable, fast-paced but essentially inconsequential film, play, or other piece of entertainment. 

  • A decisive victory; a game, match etc. which is won easily. 

  • A period of boisterous play, a frolic; now especially, a bout of sexual activity, especially when illicit. 

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