WordNet (r) 3.0 (2006):

Ninth of Ab
    n 1: (Judaism) a major fast day on the Jewish calendar
         commemorating the destruction of the temples in Jerusalem
         [syn: Tishah b'Av, Tishah b'Ab, Tisha b'Av, Tisha
         b'Ab, Ninth of Av, Ninth of Ab, Fast of Av, Fast of
         Ab]