What is "ninety-nines"

alt. (ninety-nine English) n. (ninety-nine English)

The Ninety-Nines: International Organization of Women Pilots, also known as 99s, is an international organization for female pilots that provides professional opportunities to women in aviation. The organization was founded on November 2, 1929, at Curtiss Field, Valley Stream, New York, for the mutual support and advancement of women pilots. All 117 women pilots licensed at the time were invited, and the group is named for the 99 of them who attended the meeting or expressed an interest in forming a group.