The Collaborative International Dictionary of English v.0.48:
Maestro \Ma*es"tro\ (m[imac]s"tr[-o]; It. m[aum]*[asl]s"tr[-o]), n. [It., fr. L. magister. See Master.] A master in any art, especially in music; a composer or orchestra conductor. [1913 Webster +PJC]WordNet (r) 3.0 (2006):
maestro n 1: an artist of consummate skill; "a master of the violin"; "one of the old masters" [syn: maestro, master]