IPA: /traɪˈʌmfəˌlɪzəm/
KK: /traɪˈʌmfəˌlɪzəm/
A belief or attitude that one's own beliefs, especially in politics or religion, are better than those of others, often accompanied by a sense of pride or superiority.
The politician's triumphalism was evident in his speech, where he claimed that his party's policies were the best for the country.
Triumphalism is formed from "triumphus" (from Latin, meaning a great victory or celebration) and the suffix "-ism" (meaning a doctrine or belief). The word refers to the belief in or celebration of one's own victory or superiority.
Think of 'triumph' as a great victory and '-ism' as a belief — so triumphalism is the belief in celebrating one's own victories.