Three times; thrice.
彼は会議に三度遅刻した。
He was late to the meeting three times.
その選手は今季三度の優勝を果たした。
That athlete achieved victory three times this season.
説明を三度聞いて、ようやく意味が分かった。
After hearing the explanation three times, I finally understood the meaning.
In music, an interval of a third (major or minor); as in a chord built of thirds.
その和音は三度堆積の和音で、温かい響きがある。
That chord is stacked in thirds and has a warm sound.
メロディーが三度上がる部分が曲のクライマックスだ。
The part where the melody rises by a third is the climax of the piece.