A student asked if しまった (the English equivalent for “oh shit”) is the past tense Ta-form of the word しまう. In lesson 18 of the Japanese textbook Genki, the grammar point Te-form + しまう in introduced and I believe this question came about from a student who might have heard it in an anime or read it in a manga.

In general, there are two uses of the phrase しまった. Here are the differences.

1: してしまった

Here the Te-form + しまった is used which implies that something was done to completion and or something was done with some regret. This is the form that is introduced in chapter 18 of the Genki textbook.

2: あっ、しまった

This is slightly different from the first in that there is no Te-form being used. Other vocabulary words like こまる, わかる,or  できる when used in the past tense Ta-form become こまった, わかった, and できた. The question was: is しまった the past tense Ta-form of the verb しまう.

Simply the answer is yes. However, there are a few different meanings associated with the dictionary form of the word しまう. しまうcan also be written as 仕舞う, 終う, or 了う  which has several similar meanings all which can be found here in the goo dictionary. Essentially, to finish, shut down, or put something away. When written in the past tense Ta-form the word means, “something you inadvertently say when you make a mistake.” In this case, the kanji associated would be 仕舞った.

However, there are some exceptions when しまった would not be the past tense Ta-form of しまう. For example the following Ta-forms are also read しまった; 閉まった, 締まった, 絞まった, (meaning to close, tighten, to strangle) but come from the u-verb しまる.

So, if you are asking if しまった comes from しまう, I couldn’t answer yes or no. It could come from しまる or しまう. But しまった (meaning “oops” or “oh shit”) does come from しまう and so does the Te-form + しまった.