-지 못하다
cannot, be unable to — long form
The written counterpart of 못. Same claim of inability, built as an ending rather than a word in front.
Build it
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When to use it
Attach -지 to the stem and conjugate 못하다: 가 + 지 못하다 gives 가지 못해요. As with -지 않다, there is no vowel rule and 하다 verbs stay intact: 공부하지 못했어요.
It reports that something was beyond reach — blocked by circumstance, by ability, or by time. Because the long form carries more weight, it often appears where the speaker wants to sound regretful or formal: 참석하지 못해 죄송합니다.
Like 못, it belongs with action verbs. With adjectives the construction exists but means something narrower — 좋지 못하다 is a softened way of saying “not good,” closer to “less than ideal” than to “cannot be good.”
How to attach it
| Stem type | Form | Example |
|---|---|---|
| Any action verb | -지 못하다 | 가다 → 가지 못해요 |
| 하다 verbs | no splitting | 공부하지 못했어요 |
| Past | -지 못했다 | 자지 못했어요 |
| Formal | -지 못합니다 | 참석하지 못합니다 |
| Spacing | 못하다 is one word | 가지 못해요 — not 가지 못 해요 |
| Short form | 못 + verb | 못 갔어요 |
In use
시간이 없어서 가지 못했어요.
I couldn’t go because I didn’t have time.
결과가 기대에 미치지 못했습니다.
The result fell short of expectations.
그 부탁은 들어주지 못할 것 같아요.
I’m afraid I can’t grant that request.
회의에 참석하지 못해 죄송합니다.
I’m sorry I couldn’t attend the meeting.
아직 한국어를 잘하지 못해요.
I still can’t speak Korean well.
어제는 잠을 자지 못했어요.
I wasn’t able to sleep last night.
Compared with
못
Identical meaning. 못 is what you say; -지 못하다 is what you write, and what you reach for when apologising formally.
못 갔어요. (speech) / 가지 못했습니다. (writing)
-지 않다
One word apart, opposite implications. 않다 says it did not happen; 못하다 says it could not.
가지 않았어요. (didn’t go) / 가지 못했어요. (couldn’t go)
-(으)ㄹ 수 없다
Also “cannot,” but aimed at impossibility in principle rather than a specific failed attempt. Rules and physical limits take this form.
여기에 주차할 수 없어요. (not permitted) / 어제 주차하지 못했어요. (couldn’t find a spot)
Watch out
시간이 없어서 공부 하지 못했어요.
시간이 없어서 공부하지 못했어요.
This ending keeps 하다 verbs whole. Splitting belongs to the short form: 공부 못 했어요.
어제 회의에 가지 않았어요. — meaning “I couldn’t go”
어제 회의에 가지 못했어요.
않다 suggests you decided against it. If something prevented you, 못하다 is the accurate and more courteous choice.
답을 찾지 못 했어요.
답을 찾지 못했어요.
못하다 is a single word here, so no space appears inside it. The space only exists in the short form, 못 찾았어요.
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