to finish completely; to do regrettably

Te-form plus しまう has two uses: completing an action entirely, or doing something regrettable or unintended. Context decides which reading applies. In casual speech it contracts to ちゃう and じゃう (食べちゃった, 飲んじゃった).

Examples

• 宿題しゅくだいを全部ぜんぶやってしまいました。

  Shukudai o zenbu yatte shimaimashita.

  I finished all my homework.

• 電車でんしゃに傘かさを忘わすれてしまいました。

  Densha ni kasa o wasurete shimaimashita.

  I accidentally left my umbrella on the train.

Vocabulary in these examples

• 宿題 homework
• 全部 all; everything
• やる to do
• 電車 train
• 傘 umbrella
• 忘れる to forget

Related patterns · Te-form compounds

• 〜ておく to do in advance, to leave as is
• 〜てみる to try doing and see
• 〜ていく to go on doing, to change from now on
• 〜てくる to start to, to have changed up to now