Source : Webster's Revised Unabridged Dictionary (1913)

Signor \Si*gnor"\, Signore \Si*gno"re\, n. [It. See {Seignior}.]
   Sir; Mr.; -- a title of address or respect among the
   Italians. Before a noun the form is Signor.

Source : WordNet®

signora
     n : an Italian title of address equivalent to Mrs. when used
         before a name
     [also: {signore} (pl)]

signore
     n : an Italian title of respect for a man; equivalent to the
         English `sir'; used separately (not prefixed to his name)

signore
     See {signora}