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9/11

or 9-11

[nahyn-i-lev-uh n]
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  1. September 11, 2001: the day on which Islamic terrorists, believed to be part of the Al-Qaeda network, hijacked four commercial airplanes and crashed two of them into the World Trade Center in New York City and a third one into the Pentagon in Virginia: the fourth plane crashed into a field in rural Pennsylvania.
Also called nine-elev·en.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for nine-eleven

Historical Examples

  • Miss Violet Mordaunt traveled to London this morning by the nine-eleven train.

    The Late Tenant

    Louis Tracy


British Dictionary definitions for nine-eleven

nine-eleven

9-11 or 9/11

noun
  1. the 11th of September 2001, the day on which the twin towers of the World Trade Center in New York were flown into and destroyed by aeroplanes hijacked by Islamic fundamentalistsAlso called: September eleven

Word Origin

C21: from the US custom of expressing dates in figures, the day of the month following the number of the month
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012