Kanji: 万歳 or 万才
Japanese: banzai
Simplified Chinese: 万岁
Traditional Chinese: 萬歳
Mandarin Chinese: wansui

Originally an exclamation of jubilation and praise to an emperor or a king, in conjunction with body gestures. In the 16th century Chinese literature Journey to the West, the Monkey King (Son Goku in Japanese translations) is hailed by his obsequious followers with three cheers: "wansui! wansui! wan-wansui!!" with three bows. The Japanese word banzai comes from the Chinese word wansui, literally meaning ten thousand years.

During WWII, a crowd of Japanese would shout banzai three times in unison to celebrate a victory: "Tenno heika (the emperor) banzai! Banzai! Banzai!"

Chairman Mao, who was a Chinese Communist leader of the past, was also praised with shouts of wansui by emotionally charged crowds, where each individuals held onto little red books. Chairman Mao happened to be a big fan of Monkey King, by the way.

In Japan nowadays, a "banzai!" exclamation is usually a celebratory expression of jubilation without any connotation of praise to an authority or higher power. (e.g.: "Banzai! I got into Nerd College!" or "Banzai! I won the lottery.") The act of raising both arms is also called a banzai in Japan, since people raise both hands high up with each shout of "banzai!"