KoreanSum

Verbs · 르 irregular

모르다 conjugation

to not know · moreuda · sounds like [모르다]

Short answer: “To not know” in Korean is 모르다 (moreuda). Polite present: 몰라요 (mollayo); past: 몰랐어요 (mollasseoyo); future: 모를 거예요. It is a 르 irregular verb.

Opposite: 알다 — to know

Note: Koreans don’t say 안 몰라요 — the opposite word 알다 (알아요) is used instead.

모르다 in sentences

All forms of 모르다

Present
Polite (해요) is the everyday safe choice; formal (합니다) is for news, announcements and work; casual (반말) is for close friends and younger people.
FormKoreanSounds likeRomanized
polite-아/어요몰라요[몰라요]mollayo
formal-(스)ㅂ니다모릅니다[모름니다]moreumnida
casual-아/어몰라[몰라]molla
plain (written)-(느)ㄴ다모른다[모른다]moreunda
formal question-(스)ㅂ니까?모릅니까?[모름니까]moreumnikka?
is …ing (polite)-고 있어요모르고 있어요[모르고 이써요]moreugo isseoyo
Past
FormKoreanSounds likeRomanized
polite-았/었어요몰랐어요[몰라써요]mollasseoyo
formal-았/었습니다몰랐습니다[몰랃씀니다]mollatseumnida
casual-았/었어몰랐어[몰라써]mollasseo
plain (written)-았/었다몰랐다[몰랃따]mollatda
Future
FormKoreanSounds likeRomanized
polite — will-(으)ㄹ 거예요모를 거예요[모를 꺼예요]moreul geoyeyo
formal-(으)ㄹ 겁니다모를 겁니다[모를 껌니다]moreul geomnida
casual-(으)ㄹ 거야모를 거야[모를 꺼야]moreul geoya
formal — I will (intention)-겠습니다모르겠습니다[모르겓씀니다]moreugetseumnida
Negative
FormKoreanSounds likeRomanized
not (long)-지 않아요모르지 않아요[모르지 아나요]moreuji anayo
Honorific
Add -(으)시- when the subject is someone you respect (a teacher, a customer, an older person) — not yourself.
FormKoreanSounds likeRomanized
honorific — present-(으)세요모르세요[모르세요]moreuseyo
honorific — past-(으)셨어요모르셨어요[모르셔써요]moreusyeosseoyo
honorific — formal-(으)십니다모르십니다[모르심니다]moreusimnida
Requests
FormKoreanSounds likeRomanized
please …-(으)세요모르세요[모르세요]moreuseyo
please … (for me)-아/어 주세요몰라 주세요[몰라 주세요]molla juseyo
please don’t …-지 마세요모르지 마세요[모르지 마세요]moreuji maseyo
let’s … (formal)-(으)ㅂ시다모릅시다[모릅씨다]moreupsida
let’s … (casual)-자모르자[모르자]moreuja
do … ! (casual command)-아/어라몰라라[몰라라]mollara
Connecting
FormKoreanSounds likeRomanized
… and-고모르고[모르고]moreugo
… so / and then-아/어서몰라서[몰라서]mollaseo
if …-(으)면모르면[모르면]moreumyeon
… but-지만모르지만[모르지만]moreujiman
because …-(으)니까모르니까[모르니까]moreunikka
… and / but (background)-는데모르는데[모르는데]moreuneunde
even if …-아/어도몰라도[몰라도]mollado
while …-(으)면서모르면서[모르면서]moreumyeonseo
in order to …-(으)려고모르려고[모르려고]moreuryeogo
(go) to …-(으)러모르러[모르러]moreureo
before …-기 전에모르기 전에[모르기 저네]moreugi jeone
after …-(으)ㄴ 후에모른 후에[모른 후에]moreun hue
Describing a noun
These go before a noun: “the food (that) I ate”, “a cold day”.
FormKoreanSounds likeRomanized
(that) … now-는모르는[모르는]moreuneun
(that) …ed-(으)ㄴ모른[모른]moreun
(that) will …-(으)ㄹ모를[모를]moreul
Useful patterns
FormKoreanSounds likeRomanized
I want to …-고 싶어요모르고 싶어요[모르고 시퍼요]moreugo sipeoyo
can …-(으)ㄹ 수 있어요모를 수 있어요[모를 쑤 이써요]moreul su isseoyo
cannot …-(으)ㄹ 수 없어요모를 수 없어요[모를 쑤 업써요]moreul su eopseoyo
have to …-아/어야 해요몰라야 해요[몰라야 해요]mollaya haeyo
may … / it’s OK to …-아/어도 돼요몰라도 돼요[몰라도 돼요]mollado dwaeyo
must not …-(으)면 안 돼요모르면 안 돼요[모르면 안 돼요]moreumyeon an dwaeyo
…ing (noun)-기모르기[모르기]moreugi

How 모르다 changes

르 irregular: before 아/어, 르 loses its vowel and an extra ㄹ appears → 몰라요, 몰랐어요. Other endings are regular: 모르면, 모릅니다.

How every verb type works → · Why it sounds like that →

Questions

How do you say “not know” in Korean?

“To not know” is 모르다 (moreuda), pronounced [모르다]. In a sentence: 그 단어는 몰라요. — I don’t know that word.

What is the past tense of 모르다?

몰랐어요 (mollasseoyo) is the polite past tense of 모르다 (“to not know”). Formal: 몰랐습니다; casual: 몰랐어.

How do you say 모르다 politely?

Everyday polite: 몰라요 (mollayo). Formal: 모릅니다. Casual, with close friends: 몰라.

Is 모르다 irregular?

Yes — 르 irregular: before 아/어, 르 loses its vowel and an extra ㄹ appears → 몰라요, 몰랐어요. Other endings are regular: 모르면, 모릅니다.

More 르 irregular words like 모르다

Look up another word

Forms follow 한글 맞춤법 (Korean spelling rules); pronunciation follows 표준 발음법 and romanization follows 국어의 로마자 표기법 (Revised Romanization). Last updated October 16, 2026. How we check