Verbs · 르 irregular

흐르다 conjugation

to flow · heureuda · sounds like [흐르다]

Short answer: “To flow” in Korean is 흐르다 (heureuda). Polite present: 흘러요 (heulleoyo); past: 흘렀어요 (heulleosseoyo); future: 흐를 거예요. It is a 르 irregular verb.

Present흘러요[흘러요] · heulleoyo
Past흘렀어요[흘러써요] · heulleosseoyo
Future흐를 거예요[흐를 꺼예요] · heureul geoyeyo
Negative안 흘러요[안 흘러요] · an heulleoyo

흐르다 in sentences

강물이 천천히 흘러요.The river flows slowly.
시간이 빨리 흘렀어요.Time passed quickly.

All forms of 흐르다

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.
Form	Korean	Sounds like	Romanized
polite-아/어요	흘러요	[흘러요]	heulleoyo
formal-(스)ㅂ니다	흐릅니다	[흐름니다]	heureumnida
casual-아/어	흘러	[흘러]	heulleo
plain (written)-(느)ㄴ다	흐른다	[흐른다]	heureunda
formal question-(스)ㅂ니까?	흐릅니까?	[흐름니까]	heureumnikka?
is …ing (polite)-고 있어요	흐르고 있어요	[흐르고 이써요]	heureugo isseoyo

Past
Form	Korean	Sounds like	Romanized
polite-았/었어요	흘렀어요	[흘러써요]	heulleosseoyo
formal-았/었습니다	흘렀습니다	[흘럳씀니다]	heulleotseumnida
casual-았/었어	흘렀어	[흘러써]	heulleosseo
plain (written)-았/었다	흘렀다	[흘럳따]	heulleotda

Future
Form	Korean	Sounds like	Romanized
polite — will-(으)ㄹ 거예요	흐를 거예요	[흐를 꺼예요]	heureul geoyeyo
formal-(으)ㄹ 겁니다	흐를 겁니다	[흐를 껌니다]	heureul geomnida
casual-(으)ㄹ 거야	흐를 거야	[흐를 꺼야]	heureul geoya
formal — I will (intention)-겠습니다	흐르겠습니다	[흐르겓씀니다]	heureugetseumnida

Negative
Form	Korean	Sounds like	Romanized
not (short)안 …	안 흘러요	[안 흘러요]	an heulleoyo
did not안 …았/었어요	안 흘렀어요	[안 흘러써요]	an heulleosseoyo
not (long)-지 않아요	흐르지 않아요	[흐르지 아나요]	heureuji anayo
cannot못 …	못 흘러요	[모틀러요]	mot heulleoyo

Honorific
Add -(으)시- when the subject is someone you respect (a teacher, a customer, an older person) — not yourself.
Form	Korean	Sounds like	Romanized
honorific — present-(으)세요	흐르세요	[흐르세요]	heureuseyo
honorific — past-(으)셨어요	흐르셨어요	[흐르셔써요]	heureusyeosseoyo
honorific — formal-(으)십니다	흐르십니다	[흐르심니다]	heureusimnida

Connecting
Form	Korean	Sounds like	Romanized
… and-고	흐르고	[흐르고]	heureugo
… so / and then-아/어서	흘러서	[흘러서]	heulleoseo
if …-(으)면	흐르면	[흐르면]	heureumyeon
… but-지만	흐르지만	[흐르지만]	heureujiman
because …-(으)니까	흐르니까	[흐르니까]	heureunikka
… and / but (background)-는데	흐르는데	[흐르는데]	heureuneunde
even if …-아/어도	흘러도	[흘러도]	heulleodo
while …-(으)면서	흐르면서	[흐르면서]	heureumyeonseo
before …-기 전에	흐르기 전에	[흐르기 저네]	heureugi jeone
after …-(으)ㄴ 후에	흐른 후에	[흐른 후에]	heureun hue

Describing a noun
These go before a noun: “the food (that) I ate”, “a cold day”.
Form	Korean	Sounds like	Romanized
(that) … now-는	흐르는	[흐르는]	heureuneun
(that) …ed-(으)ㄴ	흐른	[흐른]	heureun
(that) will …-(으)ㄹ	흐를	[흐를]	heureul

Useful patterns
Form	Korean	Sounds like	Romanized
I want to …-고 싶어요	흐르고 싶어요	[흐르고 시퍼요]	heureugo sipeoyo
can …-(으)ㄹ 수 있어요	흐를 수 있어요	[흐를 쑤 이써요]	heureul su isseoyo
cannot …-(으)ㄹ 수 없어요	흐를 수 없어요	[흐를 쑤 업써요]	heureul su eopseoyo
have to …-아/어야 해요	흘러야 해요	[흘러야 해요]	heulleoya haeyo
may … / it’s OK to …-아/어도 돼요	흘러도 돼요	[흘러도 돼요]	heulleodo dwaeyo
must not …-(으)면 안 돼요	흐르면 안 돼요	[흐르면 안 돼요]	heureumyeon an dwaeyo
…ing (noun)-기	흐르기	[흐르기]	heureugi

How 흐르다 changes

르 irregular: before 아/어, 르 loses its vowel and an extra ㄹ appears → 흘러요, 흘렀어요. Other endings are regular: 흐르면, 흐릅니다.

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

Questions

How do you say “flow” in Korean?

“To flow” is 흐르다 (heureuda), pronounced [흐르다]. In a sentence: 강물이 천천히 흘러요. — The river flows slowly.

What is the past tense of 흐르다?

흘렀어요 (heulleosseoyo) is the polite past tense of 흐르다 (“to flow”). Formal: 흘렀습니다; casual: 흘렀어.

How do you say 흐르다 politely?

Everyday polite: 흘러요 (heulleoyo). Formal: 흐릅니다. Casual, with close friends: 흘러.

Is 흐르다 irregular?

Yes — 르 irregular: before 아/어, 르 loses its vowel and an extra ㄹ appears → 흘러요, 흘렀어요. Other endings are regular: 흐르면, 흐릅니다.

More 르 irregular words like 흐르다

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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