noun
final performance; closing day; last show
Used for the final day or performance of a theatrical run, concert series, or similar entertainment event.
今日はこの舞台の千秋楽です。
Today is the final performance of this stage play.
千秋楽のチケットはすぐに売り切れた。
Tickets for the closing day sold out immediately.
noun
final day of a sumo tournament
Specifically refers to the last day of a sumo tournament (basho).
千秋楽に優勝が決まった。
The championship was decided on the final day of the tournament.