Source : Webster's Revised Unabridged Dictionary (1913)

Maestro \Ma*es"tro\, n. [It., fr. L. magister. See {Master}.]
   A master in any art, especially in music; a composer.

Source : WordNet®

maestro
     n : an artist of consummate skill; "a master of the violin";
         "one of the old masters" [syn: {master}]
     [also: {maestri} (pl)]