Key Facts
- Hangul: 모르다 (moreuda)
- Meaning: to not know
- Level: A1
- Stem: 모르
- Class: 르-irregular
- Object marking: transitive
What Does 모르다 Mean?
모르다 means to lack knowledge of something or someone, as in 이름을 모르다 (not to know a name). It is the usual reply to a direct question: 몰라요 says 'I don't know'.
Note that 모르다 is a verb in its own right, even though its meaning is the reverse of 알다.
Meaning in brief:
- to not know. Lack knowledge of something or someone, as in 이름을 모르다.
How Is 모르다 Used?
The thing that is not known takes 을/를, so the sentence 답을 몰라요 means 'I don't know the answer'. The honorific is 모르세요.
One form is missing on purpose: the want-to form. Not knowing is not something you normally choose, so -고 싶다 is rarely used with 모르다, and the table below leaves that cell out.
How Do You Pronounce 모르다?
모르다 is romanized moreuda. The ㄹ between vowels is a light tap, and ㅡ is unrounded, with spread lips. In 몰라요 the two ㄹ sounds meet and become a long, clear l: mol-la-yo.
Example Sentences
저는 그 길을 몰라요.
I don't know that road.
This is the polite present form. The route 그 길을 takes 을/를 and the verb is in the polite present. Notice the form 몰라요, with ㄹ written twice.
어제는 그 사실을 몰랐어요.
Yesterday I didn't know that.
This is the polite past form. Here the past form 몰랐어요 is paired with 어제는. The past stem is 몰랐, built from the same 르 change as the present.
한국어를 몰라서 도움이 필요해요.
I don't know Korean, so I need help.
This is the because / and then form. 몰라서 links two ideas: the cause comes first, the result second. The same 몰라 stem appears before 서.
Moreuda Conjugation: What Are the Forms of 모르다?
Watch what happens to the final syllable. 르 splits: the ㅡ is lost, the ㄹ moves back to the previous syllable, and a new ㄹ plus 라 or 러 follows. That is why you see 몰라요, 몰랐어요, 몰라 and 몰라서. Before a consonant ending, the stem stays as 모르, as in 모르면, 모르는 and 모릅니다.
모르다
| Form | Korean | Romanization | Rule |
|---|---|---|---|
| Polite present | 몰라요 | ||
| Polite past | 몰랐어요 | ||
| Polite future (plan) | 모를 거예요 | ||
| Polite future (intention or guess) | 모르겠어요 | ||
| Formal present | 모릅니다 | ||
| Formal past | 몰랐습니다 | ||
| Formal future | 모를 것입니다 | ||
| Casual present | 몰라 | ||
| Casual past | 몰랐어 | ||
| Casual future | 모를 거야 | ||
| Want to (polite) | |||
| Honorific polite | 모르세요 | ||
| Because / and then | 몰라서 | ||
| If (conditional) | 모르면 | ||
| Present modifier (before a noun) | 모르는 | ||
| Past modifier (before a noun) | 모른 | ||
| Future modifier (before a noun) | 모를 | ||
| Negative with 안 (short) | 안 몰라요 | ||
| Negative (long form) | 모르지 않아요 |
| Form | Korean | Pronunciation |
|---|---|---|
| Polite present | 몰라요 | - |
| Polite past | 몰랐어요 | [몰라써요] |
| Polite future (plan) | 모를 거예요 | [모를꺼예요] |
| Polite future (guess) | 모르겠어요 | [모르게써요] |
| Formal present | 모릅니다 | [모름니다] |
| Formal past | 몰랐습니다 | [몰랃씀니다] |
| Formal future | 모를 것입니다 | [모를꺼심니다] |
| Casual present | 몰라 | - |
| Casual past | 몰랐어 | [몰라써] |
| Casual future | 모를 거야 | [모를꺼야] |
| Want to (polite) | None | - |
| Honorific polite | 모르세요 | - |
| Because / and then | 몰라서 | - |
| If (conditional) | 모르면 | - |
| Modifier, present | 모르는 | - |
| Modifier, past | 모른 | - |
| Modifier, future | 모를 | - |
| Short negative | 안 몰라요 | - |
| Long negative | 모르지 않아요 | [모르지 아나요] |
The want-to cell is left out, as explained above.
Is 모르다 Regular or Irregular?
모르다 is a 르-irregular verb: before 아/어 the ㅡ of 르 drops and an extra ㄹ appears (모르다 -> 몰라요); before consonant endings the stem stays 모르. In the forms that need 아 or 어 you get ㄹ + 라, because the vowel before 르 is ㅗ. That one rule explains the whole row of forms, so it pays to read the 르 irregular lesson with the table beside you.
Common Mistake with 모르다
Wrong: ✗ 모르아요
Correct: ✓ 몰라요
Why: 모르다 is a 르-irregular verb: 르 becomes ㄹ + 라/러 (몰라요, 몰랐어요), so 모르아요 or 모르어요 is wrong. Learners who treat 모르다 as regular produce 모르아요 or 모르어요. The correct polite present is 몰라요, because the 르 change is compulsory, not optional.
Similar Words
| Word | How it differs from 모르다 |
|---|---|
| 알다 | 모르다 is to not know; 알다 is to know. |
| 이해하지 못하다 | 모르다 means lacking knowledge; 이해하지 못하다 means failing to understand something you heard or read. |
Use 알다 for the positive 'know'. For 'I don't understand', 이해하지 못하다 is the explicit choice, though everyday speech often uses 모르다 here too.
Asking a Classmate about Homework
A student missed the homework instructions and asks a classmate for help after class.
Mina
오늘 숙제가 뭐예요? 잘 모르겠어요.
Oneul sukjega mwoyeyo? Jal moreugesseoyo.
What is today’s homework? I’m not sure.
Alex
삼 쪽이에요.
Sam jjogiyeyo.
Page three.
Mina
아, 몰랐어요. 고마워요.
A, mollasseoyo. Gomawoyo.
Oh, I didn’t know. Thank you.
모르겠어요 expresses uncertainty now. 몰랐어요 looks back at the information the speaker lacked before the answer. The past can acknowledge newly learned information even when the conversation is happening right now.
Phrases for Uncertainty and Unfamiliar Things
잘 모르겠어요 means “I'm not sure” or “I don't really know”. 잘 literally means “well”, so it softens the answer by saying the speaker does not know well enough. It is useful when you need another explanation and want to keep the conversation going.
모르는 사람 means “someone you don't know”, often a stranger. 모르는 단어 is an unfamiliar word. The modifier 모르는 keeps 르 because the ending is 는. Recognizing this form helps with classroom instructions about finding unfamiliar vocabulary.
아무도 몰라요 means “nobody knows”. 아무도 pairs with the negative meaning already contained in 모르다. The simple statement needs no extra 안. 아무것도 몰라요 means “I don't know anything”, with the thing unknown rather than the people who lack knowledge in focus.
Where Will You Hear 모르다?
In lessons and service encounters, 잘 모르겠어요 is a useful reply when instructions remain unclear. A bare 몰라요 is grammatical and polite in form, but a brief answer with no explanation can sound abrupt. 잘 모르겠어요 often leaves more room for the other person to help.
In dramas, 몰랐어요 can express surprise at a fact just revealed. In a formal interview, 모릅니다 is a direct statement that the speaker does not know. Neither form explains whether the speaker forgot, never learned, or failed to understand; add context when that distinction matters.
What Makes 모르다 Tricky?
The negative forms in the table are double negatives in meaning. 모르지 않아요 means roughly “it's not that I don't know”; it can imply some knowledge. 안 몰라요 is unusual outside an emphatic exchange. For an ordinary “I don't know”, 몰라요 already contains the negative meaning.
| Related word | Meaning | Useful note |
|---|---|---|
| 질문 | question | Names what you ask when information is missing. |
| 답 | answer | Takes 을 in 답을 몰라요. |
| 이해하다 | to understand | Focuses on grasping meaning. |
| 알려주다 | to tell / let someone know | Describes supplying the missing information. |
The Korean questions lesson helps turn uncertainty into a specific question.
Mini Drill: Keep or Change 르?
- Give the polite present of 모르다.
- Give the polite past.
- Complete “an unfamiliar word”: ___ 단어.
- Complete “if you don't know”: ___ .
Show uncertainty drill answers
- 몰라요.
- 몰랐어요.
- 모르는 단어. Keep 르 before 는.
- 모르면. This ending does not trigger the doubled ㄹ.
Quick Self-Test
- Does 몰라요 need 안 to mean “I don't know”?
- What does 잘 add in 잘 모르겠어요?
- Does 몰랐어요 necessarily mean “I forgot”?
Show answers
- No. 모르다 already means not knowing.
- It softens the uncertainty: “I don't know well enough” or “I'm not sure”.
- No. It states a past lack of knowledge, without explaining its cause.
Frequently Asked Questions
How Do I Say 'I Don't Know' in Korean?
Say 몰라요. It is the polite present of 모르다. With friends, use the shorter casual form 몰라.
Why Is There No Want-to Form of This Verb?
Not knowing is not something you usually choose, so the want-to pattern -고 싶다 is rarely used with this verb. To explain a consequence of not knowing, use 몰라서 instead, as in 한국어를 몰라서 도움이 필요해요.
What Is the Difference from 알다?
모르다 is to not know and 알다 is to know. Both are verbs, and 알다 has its own page in the dictionary.
How Is the past Formed?
It is 몰랐어요. The 르-irregular change applies in the past as well as in the present, so the stem plus the past ending becomes 몰랐어요.
Can I Use 모르다 for Not Understanding a Sentence?
Yes, in everyday speech: 모르겠어요 is a common, polite way to say 'I'm not sure' or 'I don't get it'. 이해하지 못하다 is more explicit when you heard the words but could not follow their meaning.
Which Words Are Related to 모르다?
What Should You Learn Next?
Read the 르 irregular lesson, then open the conjugator and test 모르다 against 알다. Say the three examples aloud and write one sentence with 몰라서 for yourself.
Class lesson: Korean 르 Irregular Verbs. Tool: Korean verb conjugator.