I know if you say ～てしまった – it can mean either, “unfortunately” or it can mean “completely”.
この本全部読んじゃった – “I unfortunately read through the whole book” (unfortunately because it ended up SUCH a waste of time) – OR “I read through the whole book completely” (I read it through all the way, completely finishing it off)
I’m already a little shady on how to differentiate those meanings, but I suppose that’s one of those things that really relies on context.
BUT…
On the subject of the “completely” definition – I noticed ～切る as a suffix does the same thing. So what would be the difference between that and て切る？
Example:
食べてしまった versus 食べ切った – what’s the difference in meaning? In feeling?
4 comments
i think てしまう emphasizes the permanence of the action (/“i can’t take it back” sort of nuance) whereas 切る is more just completing some action. like read the whole book, ate all the food, etc
disclaimer i am merely a simple learner not a nihongo master
-切る, meaning “to do completely,” often doesn’t have the sense of regret or resolve that てしまう has. 〜切る can also be used for a discrete action.
Edit: -切る is often a quick, decisive action too.
タバコをその一本吸い切って、「今からやめてしまう」と山田さんは言いました。言いながらもう一本を吸いはじめてしまいました。
Finishing that one cigarette, Yamada said “Starting right now I’m quitting cold turkey.” As he was saying this, he started smoking another.
i like to translate てしまう as “went and” or “gone and”
またペンを落ちてしまった
i went and dropped my pen again
おっと、全てを食べてしまった
whoops, i’ve gone and eaten the whole thing
I think you overemphasize the “unfortunateness” of てしまう in your understanding of it. The way natives use it, it’s not even always negative, it’s more like “whoops hehe” or “darn, whoops”. Like others said, it focuses on the unreclaimability of the action, like the fact that you’ve done it and you can’t take it back. It’s useful for when you do things by accident.
切る just means to do something through to the end.
So, 食べてしまう “to eat something (with the sense of “whoops, I can’t take that back”)”
食べ切る “to eat the entirety of something”