Fromdes- +‎abafar(“suffocate”).

desabafar (first-person singular presentdesabafo,first-person singular preteritedesabafei,past participledesabafado)

1. tounburden
2. toair

   Synonym:arejar

3. (by extension) toget off one's chest; tovent one's spleen,let off steam,rant

   Synonyms:desafogar,expressar,exteriorizar

   Escrevo paradesabafar, quando não tem ninguém para me ouvir.

   I write tovent when there is no one to listen to me.