Source : Webster's Revised Unabridged Dictionary (1913)

Quietus \Qui*e"tus\, n. [LL. quietus quit, discharged, L., at
   rest, quiet, dead. See {Quiet}, a., and cf. {Quit}, a.]
   Final discharge or acquittance, as from debt or obligation;
   that which silences claims; (Fig.) rest; death.

         When he himself might his quietus make With a bare
         bodkin.                                  --Shak.

Source : WordNet®

quietus
     n : euphemisms for death (based on an analogy between lying in a
         bed and in a tomb); "she was laid to rest beside her
         husband"; "they had to put their family pet to sleep"
         [syn: {rest}, {eternal rest}, {sleep}, {eternal sleep}]