Master.

• 1.  male teacher.
• 2.  man who has others working under him.
• 3.  the Master = Jesus Christ.
• 4.  Master of arts/Science etc = holder of the second university degree.
• 5.  (with a boy’s name) up to about 14 years of age.
• 6.  old masters = the great painters of 13th to 17th century.

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Maestro = eminent music composer , teacher of music or conductor( Plural – maestri).

• Johnson( popularly known as Johnson master) was a great maestro and he composed a number of soulful melodies.
• Ouseppachan is a violin maestro and music composer.
• Late Balabhaskar and late Ustad Gohar Ali Khan were great Indian violin maestri.