1. 
[syn: upset, discompose, untune, disconcert, discomfit]
2.  cause to be out of tune; 
- Example: "Don't untune that string!"
The Collaborative International Dictionary of English v.0.48:
Untune \Un*tune"\, v. t. [1st pref. un- + tune.]
   To make incapable of harmony, or of harmonious action; to put
   out of tune. --Shak.
   [1913 Webster]
WordNet (r) 3.0 (2006):
untune
    v 1: cause to lose one's composure [syn: upset, discompose,
         untune, disconcert, discomfit]
    2: cause to be out of tune; "Don't untune that string!" [ant:
       tune, tune up]