1. Noun

   the end; closing; being done for

   Usually written using kana alonePolite (teineigo) languagesee 仕舞い

   今日はこれでおしまいにしてはどうでしょう。

2. Interjection (kandoushi)

   that's it; that's enough; that's all

   Usually written using kana alone

Also written お終い【おしまい】oshimai