Lookups spiked on September 11, 2013.
Hero was used this week in many commemorations and remembrances of the 9/11 attack.
First responders and military personnel are often referred to as "heroes," but many stories about the heroes of 9/11 focused on ordinary people - office workers, bystanders - who risked and gave their lives to help others.
This use is supported by the original definition of hero: "a person who is admired for great or brave acts or fine qualities."
Hero comes from a Greek word that originally referred to men of superhuman strength or courage.