What is 'letting go' and 'detachment' actually?
What are the actual sanskrit and pali terms for 'letting go' and 'detach'?

Quoting from "Re: What is the last thing to let go?":


  In the Suttas paṭinissagga and its synonym vossagga are the words that usually get translated ‘relinquishment’, ‘letting go’ and suchlike. What is relinquished is appropriation (ādāna) which is a term for taṇhā and upādāna.


And:


  Paṭinissagga (letting go) is the broad term and then nekkhamma (letting go) is a more specialised one. Nekkhamma is paṭinissagga with respect to desire for sense-pleasures.