let loose vs unloose

let loose

verb
  • To free; to release from restraint. 

  • To break wind. 

  • To shout, make a loud sound, or perform a sudden, vehement action; to behave in a raucous, frenzied manner. 

unloose

verb
  • To free from a constraint. 

  • To loosen or undo (something that entangles, fastens, holds, or interlocks). 

  • To free (someone or something) from a constraint; (figuratively) to release (something which has been suppressed, such as emotions or objectionable things). 

  • To relax or slacken (something that clasps or grips, such as the arms or hands). 

  • To become loose or come off. 

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