This is the 3699th most frequent Japanese word.
おしまい
"The end" or "finished."
おしまい is used to signify the conclusion or ending of the story.
これで物語はおしまいです。
With this, the story ends.
おしまい is used to indicate the ceasing or stopping of playtime as a result.
宿題を終わらせなかったら、遊びはおしまいだよ。
If you don't finish your homework, playtime is over.
おしまい is used adverbially (as 'finally') to indicate the final event of a sequence.