Suppletive Negatives: 있다 → 없다, 알다 → 모르다, 이다 → 아니다 | Korean Grammar

By now the pattern feels automatic: to negate, drop 안 or 못 in front of the verb. But three of the most common predicates in the language refuse that treatment. Instead of adding a negator, they swap in a completely different word. Existence 있다 becomes 없다; knowledge 알다 becomes 모르다; the copula 이다 becomes 아니다. Linguists call this suppletion — the same relationship English has between "good" and "better" (not "gooder"). You can't build these negatives from parts; you memorize the partner word.

Existence and possession: 있다 → 없다

있다 means "to exist / to be (located) / to have." Its negative is not ×안 있다 — it's the dedicated word 없다, "to not exist / to not have." The two form a matched pair, and the negation is baked into the vocabulary.

지금 시간이 없어요.

jigeum sigani eopseoyo

I don't have time right now.

오늘은 약속이 없어요.

oneureun yaksogi eopseoyo

I don't have any plans today.

냉장고에 우유가 없어요.

naengjanggo-e uyuga eopseoyo

There's no milk in the fridge.

Trying to say ×안 있어요 for "there isn't" marks you instantly as a beginner. The whole "there is / there isn't" contrast in Korean runs on this one pair — 있어요 vs 없어요 — never on 안.

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있다 and 없다 are two separate dictionary words, not a verb plus a negator. So both conjugate on their own: 있었어요 / 없었어요 (was / wasn't there), 있을 거예요 / 없을 거예요 (will / won't be there). Just pick the right word; don't try to negate one into the other with 안.

Knowledge: 알다 → 모르다

알다 ("to know") has the suppletive negative 모르다 ("to not know"). Again, ×안 알아요 is wrong — the natural negative of "I know" is 몰라요.

저는 잘 몰라요.

jeoneun jal mollayo

I don't really know.

그 사람 이름을 몰라요.

geu saram ireumeul mollayo

I don't know that person's name.

길을 몰라서 한참 헤맸어요.

gireul mollaseo hancham hemaesseoyo

I didn't know the way, so I wandered around for ages.

There's a nice irony here: 알다 is a smooth ㄹ-stem verb, but its negative 모르다 belongs to a different irregular class (the 르-irregular), which is why "don't know" surfaces as 몰라요, not ×모르어요. Two unrelated stems, welded into one meaning-pair. You simply learn 알아요 / 몰라요 as a set.

The copula: 이다 → 아니다, with 이/가 on the noun

The copula 이다 ("to be [something]") negates to 아니다 ("to not be [something]"). But there's a structural twist that catches everyone: while 이다 attaches directly to the noun (학생이다), 아니다 does not. Instead the identified noun stands as its own word and takes the subject particle 이/가.

Affirmative (이다 attaches)	Negative (noun + 이/가 + 아니다)
학생이에요 — is a student	학생이 아니에요 — is not a student
의사예요 — is a doctor	의사가 아니에요 — is not a doctor

저는 학생이 아니에요.

jeoneun haksaeng-i anieyo

I'm not a student.

이건 제 것이 아니에요.

igeon je geosi anieyo

This isn't mine.

그 사람은 제 친구가 아니에요.

geu sarameun je chinguga anieyo

That person isn't my friend.

The particle follows the usual rule: 이 after a consonant-final noun (학생이, 것이), 가 after a vowel-final noun (의사가, 친구가). This 이/가 is easy to drop by accident — but ×저는 학생 아니에요 (no particle) sounds off. The copula's negation gets its own full treatment on the 아니다 page.

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아니다 is a single, self-standing word (not 안 + 이다), and it inflects like an adjective: 아니에요 (informal polite), 아닙니다 (formal), 아니었어요 (past). So once you have the noun + 이/가 frame, you conjugate 아니다 itself — there's no 안 anywhere in sight.

Compound descriptives swap wholesale too

A useful ripple effect: adjectives built on 있다/없다 flip as a unit. 재미있다 ("interesting," literally "fun exists") negates not with 안 but by swapping the 있 for 없 — 재미없다 ("boring"). Same with 맛있다 → 맛없다.

Positive	Negative (swap 있 → 없)
재미있다 (fun / interesting)	재미없다 (boring)
맛있다 (tasty)	맛없다 (bland / bad-tasting)
멋있다 (cool / stylish)	멋없다 (dorky / unstylish)

이 영화 생각보다 재미없어요.

i yeonghwa saenggakboda jaemi-eopseoyo

This movie is more boring than I expected.

국이 좀 맛없어요.

gugi jom madeopseoyo

The soup is a bit bland.

Note the pronunciations: 맛있어요 → [마시써요] masisseoyo, but 맛없어요 → [마덥써요] madeopseoyo. The negative isn't ×안 맛있어요 — you replace the 있 with 없 inside the word.

But ordinary adjectives negate normally

Don't overgeneralize. Suppletion is limited to that short list. Ordinary adjectives — 크다, 비싸다, 좋다, 깨끗하다, and the rest — negate the regular way, with 안 or the long -지 않다, and never with 못.

이 방은 안 커요.

i bang-eun an keoyo

This room isn't big.

가격이 생각보다 비싸지 않아요.

gagyeogi saenggakboda bissaji anayo

The price isn't as high as I thought.

So the mental filter is: is this one of the suppletive predicates (있다, 알다, 이다) or a compound on 있다/없다? If yes, swap the whole word. If it's any other adjective or action verb, add 안 (or -지 않다) as usual.

Common Mistakes

1. ×안 있어요 for "there isn't." Existence negates to 없어요.

❌ 지금 시간이 안 있어요.

Incorrect — the negative of 있다 is the word 없다: 시간이 없어요.

✅ 지금 시간이 없어요.

jigeum sigani eopseoyo

I don't have time right now.

2. ×안 알아요 for "don't know." Knowledge negates to 몰라요.

❌ 저는 그 사람을 안 알아요.

Incorrect — the negative of 알다 is 모르다: 그 사람을 몰라요.

✅ 저는 그 사람을 몰라요.

jeoneun geu sarameul mollayo

I don't know that person.

3. Dropping the 이/가 before 아니다. The identified noun must carry the subject particle.

❌ 저는 의사 아니에요.

Incorrect — the noun needs 이/가: 저는 의사가 아니에요.

✅ 저는 의사가 아니에요.

jeoneun uisaga anieyo

I'm not a doctor.

4. Prefixing 안 to a 있다-compound. Swap 있 → 없 inside the word.

❌ 이 드라마 안 재미있어요.

Off — the natural negative is 재미없어요, not 안 재미있어요.

✅ 이 드라마 재미없어요.

i deurama jaemi-eopseoyo

This drama is boring.

Key Takeaways

Three core predicates negate by word replacement, not by adding 안/못: 있다 → 없다 (exist/have), 알다 → 모르다 (know), 이다 → 아니다 (be [something]).
With 아니다, the identified noun takes 이/가 (학생이 아니에요, 친구가 아니에요) — don't drop the particle.
Compounds on 있다/없다 flip as a unit: 재미있다 → 재미없다, 맛있다 → 맛없다.
Everything else — ordinary adjectives and action verbs — still negates the normal way with 안 or -지 않다.
The wrong instinct to unlearn: reflexively slapping 안 on everything. A short, high-frequency set carries its own built-in negative word.

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