[1] : The Collaborative International Dictionary of English v.0.48

off-key \off-key\ adj.  adv.
   deviating from the proper pitch; -- of a musical note or
   series of notes; as, an off-key note; to sing off-key.

   syn: false, sour.
        wordnet 1.5

[2] : WordNet (r) 2.0

off-key
     adj : inaccurate in pitch; "a false or sour note"; "her singing
           was off key" syn: false, sour
see also:
false sour 

Off-Key >> O Words
Off-Key, definition of term: Off-Key
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