Use of the term 7/7 to refer to the bombings on July 7th 2005 is modelled on the term 9/11, a universally-understood representation of the tragic events of September 11th 2001, when four commercial airliners were hijacked by terrorists in the United States. Two of the planes crashed into the Twin Towers of the World Trade Center in New York, and another hit the Pentagon, with more than 3000 people losing their lives. Voted Word of the Year in 2001 by the American Dialect Society, 9/11 entered the US and international lexicon practically overnight, immediately understood even in Canada, Australia and Britain, where 9/11 conventionally means November 9th, rather than September 11th.

Use of the term 7/7 to refer to the bombings on July 7th 2005 is modelled on the term 9/11, a universally-understood representation of the tragic events of September 11th 2001, when four commercial airliners were hijacked by terrorists in the United States. Two of the planes crashed into the Twin Towers of the World Trade Center in New York, and another hit the Pentagon, with more than 3000 people losing their lives. Voted Word of the Year in 2001 by the American Dialect Society, 9/11 entered the US and international lexicon practically overnight, immediately understood even in Canada, Australia and Britain, where 9/11 conventionally means November 9th, rather than September 11th.