Source : Webster's Revised Unabridged Dictionary (1913)

Falsetto \Fal*set"to\, n.; pl. {Falsettos}. [It. falsetto, dim.
   fr. L. falsus. See {False}.]
   A false or artificial voice; that voice in a man which lies
   above his natural voice; the male counter tenor or alto
   voice. See {Head voice}, under {Voice}.

Source : WordNet®

falsetto
     adj : artificially high; above the normal voice range; "a falsetto
           voice"
     n : a male singing voice with artificially high tones in an
         upper register