heroism UK /ˈhɛɹəʊɪzəm/US /ˈhɛɹoʊɪzəm/ noun1 •The qualities characteristic of a hero, such as courage, bravery, fortitude, selflessness, etc.; the display of such qualities.Certain strains of music affect me so strangely; I can never hear them without their changing my whole attitude of mind for a time, and if the effect would last, I might be capable of heroisms. — 1860 formsheroisms