hero·ism \ˈherəˌwizəm also ˈhir- or ˈhēr-\noun (-s) Etymology: French héroïsme, from héros hero (from Latin heros, from Greek hērōs) + -isme -ism — more at hero 1.: heroic conduct < the heroism of a regiment defending a position > 2.: the qualities (as courage, bravery, self-sacrifice, unselfishness) of a hero : heroic characteristics < a nation famous for the heroism of its leaders >