noun
shout of victory; triumphant cry
A traditional, often collective, shout or cry raised to celebrate a victory, especially in historical or military contexts. In modern use, it can be used figuratively for any triumphant exclamation.
戦いに勝った兵士たちは勝ちどきをあげた。
The soldiers who won the battle raised a shout of victory.
優勝が決まった瞬間、チーム全員で勝ちどきをあげた。
The moment the championship was decided, the whole team let out a triumphant cry together.
Full kanji with okurigana; very rare, mainly in older texts.
歓声 is a general cheer or joyful shout, not specifically tied to victory. 勝ちどき is explicitly a victory cry, often with a traditional or martial nuance.
万歳 is a celebratory exclamation ('banzai!') often shouted with arms raised. 勝ちどき is more of a collective roar or shout specifically for triumph, less of a set phrase.
Compound of 勝ち (kachi, 'victory', continuative form of 勝つ) and 鬨 (toki, 'war cry, battle shout'). The reading toki becomes doku due to rendaku. The kanji 鬨 is rare and often replaced by kana in modern writing.