NOUN (2)

1. an Italian courtesy title for an unmarried woman; equivalent to `Miss', it is either used alone or before a name;

2. an Italian title or form of address for an unmarried woman;

The Collaborative International Dictionary of English v.0.48:

Signorina \Si`gno*ri"na\, n. [It.]
   Miss; -- a title of address among the Italians.
   [1913 Webster]

WordNet (r) 3.0 (2006):

signorina
    n 1: an Italian courtesy title for an unmarried woman;
         equivalent to `Miss', it is either used alone or before a
         name
    2: an Italian title or form of address for an unmarried woman