KoreanSum

Verbs · ㄹ stem

알다 conjugation

to know · alda · sounds like [알다]

Short answer: “To know” in Korean is 알다 (alda). Polite present: 알아요 (arayo); past: 알았어요 (arasseoyo); future: 알 거예요. It is regular, but its ㄹ drops before ㄴ, ㅂ and ㅅ.

Opposite: 모르다 — to not know

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

알다 in sentences

All forms of 알다

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/어요알아요[아라요]arayo
formal-(스)ㅂ니다압니다[암니다]amnida
casual-아/어알아[아라]ara
plain (written)-(느)ㄴ다안다[안다]anda
formal question-(스)ㅂ니까?압니까?[암니까]amnikka?
is …ing (polite)-고 있어요알고 있어요[알고 이써요]algo isseoyo
Past
FormKoreanSounds likeRomanized
polite-았/었어요알았어요[아라써요]arasseoyo
formal-았/었습니다알았습니다[아랃씀니다]aratseumnida
casual-았/었어알았어[아라써]arasseo
plain (written)-았/었다알았다[아랃따]aratda
Future
FormKoreanSounds likeRomanized
polite — will-(으)ㄹ 거예요알 거예요[알 꺼예요]al geoyeyo
formal-(으)ㄹ 겁니다알 겁니다[알 껌니다]al geomnida
casual-(으)ㄹ 거야알 거야[알 꺼야]al geoya
formal — I will (intention)-겠습니다알겠습니다[알겓씀니다]algetseumnida
Negative
FormKoreanSounds likeRomanized
not (long)-지 않아요알지 않아요[알지 아나요]alji 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)세요아세요[아세요]aseyo
honorific — past-(으)셨어요아셨어요[아셔써요]asyeosseoyo
honorific — formal-(으)십니다아십니다[아심니다]asimnida
Requests
FormKoreanSounds likeRomanized
please …-(으)세요아세요[아세요]aseyo
please … (for me)-아/어 주세요알아 주세요[아라 주세요]ara juseyo
please don’t …-지 마세요알지 마세요[알지 마세요]alji maseyo
let’s … (formal)-(으)ㅂ시다압시다[압씨다]apsida
let’s … (casual)-자알자[알자]alja
do … ! (casual command)-아/어라알아라[아라라]arara
Connecting
FormKoreanSounds likeRomanized
… and-고알고[알고]algo
… so / and then-아/어서알아서[아라서]araseo
if …-(으)면알면[알면]almyeon
… but-지만알지만[알지만]aljiman
because …-(으)니까아니까[아니까]anikka
… and / but (background)-는데아는데[아는데]aneunde
even if …-아/어도알아도[아라도]arado
while …-(으)면서알면서[알면서]almyeonseo
in order to …-(으)려고알려고[알려고]allyeogo
(go) to …-(으)러알러[알러]alleo
before …-기 전에알기 전에[알기 저네]algi jeone
after …-(으)ㄴ 후에안 후에[안 후에]an hue
Describing a noun
These go before a noun: “the food (that) I ate”, “a cold day”.
FormKoreanSounds likeRomanized
(that) … now-는아는[아는]aneun
(that) …ed-(으)ㄴ안[안]an
(that) will …-(으)ㄹ알[알]al
Useful patterns
FormKoreanSounds likeRomanized
I want to …-고 싶어요알고 싶어요[알고 시퍼요]algo sipeoyo
can …-(으)ㄹ 수 있어요알 수 있어요[알 쑤 이써요]al su isseoyo
cannot …-(으)ㄹ 수 없어요알 수 없어요[알 쑤 업써요]al su eopseoyo
have to …-아/어야 해요알아야 해요[아라야 해요]araya haeyo
may … / it’s OK to …-아/어도 돼요알아도 돼요[아라도 돼요]arado dwaeyo
must not …-(으)면 안 돼요알면 안 돼요[알면 안 돼요]almyeon an dwaeyo
…ing (noun)-기알기[알기]algi

How 알다 changes

알다 ends in ㄹ. The ㄹ drops before ㄴ, ㅂ and ㅅ — 아는, 압니다, 아세요 — and endings written -(으) never add 으: 알면, 알. Everything else is regular: 알아요. (Grammar books count this as regular, but it trips up learners.)

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

Questions

How do you say “know” in Korean?

“To know” is 알다 (alda), pronounced [알다]. In a sentence: 그 사람 알아요? — Do you know that person?

What is the past tense of 알다?

알았어요 (arasseoyo) is the polite past tense of 알다 (“to know”). Formal: 알았습니다; casual: 알았어.

How do you say 알다 politely?

Everyday polite: 알아요 (arayo). Formal: 압니다. Casual, with close friends: 알아.

Is 알다 irregular?

No. 알다 ends in ㄹ. The ㄹ drops before ㄴ, ㅂ and ㅅ — 아는, 압니다, 아세요 — and endings written -(으) never add 으: 알면, 알. Everything else is regular: 알아요. (Grammar books count this as regular, but it trips up learners.)

More ㄹ-stem words like 알다

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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