Meaning
Can mean completing an action fully or expressing regret that something happened accidentally or undesirably.
Formation
- て form + しまう: 忘れてしまいました
- Colloquial contractions: てしまう → ちゃう, でしまう → じゃう
When to use it
- Core use
- Finish it, or do it by accident
Example
宿題を忘れてしまいました
I accidentally forgot my homework.
Important notes
- Pay attention to the word form before the construction and to the particles around it.
Common mistakes
- Do not translate the pattern word for word; first identify its function in the whole situation.