Korean Negation: 안 vs 못, 이/가 아니에요, and -지 않다
Korean negation explained: 안 means won't, 못 means can't, nouns take 이/가 아니에요, and -지 않다 / -지 못하다 are the long forms — plus polite ways to say no.
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Written by Alvin Lim Certified Korean Language Teacher (Level 2)
Korean negation runs on two little adverbs: 안 when you do not do something by choice — 고기를 안 먹어요 (I don’t eat meat) — and 못 when you cannot — 수영을 못 해요 (I can’t swim). Nouns get their own pattern: 이/가 아니에요 (is not). Add the long forms -지 않다 / -지 못하다 for formal moments, and you can decline meat, drinks, and cigarettes politely all over Korea.
Ten words you will say no to
Vocabulary first — the things Koreans most often offer, and the words that wave them off.
안 or 못: do you mean won’t or can’t?
Both go directly in front of the verb, and they are not interchangeable: 안 reports a choice — you simply do not do it — while 못 reports a wall: skill, health, schedule, or the law stops you. English folds both into one “don’t,” which is why this contrast deserves five focused minutes.
안 = do not / will not (choice): 고기를 안 먹어요 = I don’t eat meat. 못 = cannot (ability or circumstance): 수영을 못 해요 = I can’t swim. Same verb, different worlds: 술을 안 마셔요 (I don’t drink) vs 술을 못 마셔요 (I can’t drink — driving, medicine).
One trap: 하다 verbs split. 수영하다 becomes 수영 안 해요 / 수영 못 해요 — the negator slides between the noun and 하다; 안 수영해요 sounds broken. Plain verbs keep it simple: 안 가요, 못 마셔요.
”It is not water” — 이/가 아니에요
In Lesson 4 you learned 이에요/예요 to say what something IS. Its mirror, 이/가 아니에요, says what something is NOT — verbs take 안/못, nouns take 아니에요.
Consonant ending + 이 아니에요: 저는 학생이 아니에요 = I am not a student. Vowel ending + 가 아니에요: 저는 가수가 아니에요 = I am not a singer. 이거는 물이 아니에요. 술이에요! = This is not water. It’s soju!
The long forms: -지 않다 and -지 못하다
먹지 않아요 = 안 먹어요 = I don’t eat (it). 먹지 못해요 = 못 먹어요 = I can’t eat (it). One shape for every verb — no vowel matching, just stem + 지.
Meaning-wise they are identical to 안 and 못 — the difference is register. Long forms feel more formal and live in writing, signs, and announcements; spoken Korean overwhelmingly prefers the short forms. So train 안/못 as your speaking reflex and keep -지 않다 in your reading toolkit. Both 않다 and 못하다 conjugate like any verb from the 해요-form lesson: 않아요, 못해요.
아직, 전혀, 별로 — the negation entourage
Three adverbs love negatives. 아직 = yet / still: 아직 잘 못해요 (not good at it yet). 전혀 (not at all) and 별로 (not really) are negative-only: 전혀 안 마셔요, 별로 안 매워요. A positive 전혀 매워요 is simply ungrammatical — the adverb itself promises a 안, 못, or 아니에요 later in the sentence.
Saying no without drama
Watch 안 and 못 split the work across one dinner invitation:
The meat line uses 안 — a standing choice, no apology needed. The alcohol line uses 못 — circumstances forbid it tonight, quietly signaling “ask me again.” Koreans read that nuance instantly: picking the right negator is politeness, not just grammar.
FAQ
What is the real difference between 안 and 못? 안 negates by choice or plain fact: 고기를 안 먹어요 = I don’t eat meat (I choose not to). 못 negates by inability or circumstance: 수영을 못 해요 = I can’t swim. So 술을 안 마셔요 means you don’t drink; 술을 못 마셔요 means something stops you tonight — driving, medicine, health. Where does 안 go with 하다 verbs like 공부하다? Split the verb and slide 안 (or 못) right before 하다: 공부 안 해요, 수영 못 해요, 운전 안 해요. Saying 안 공부해요 sounds unnatural. This only applies to noun + 하다 verbs — plain verbs keep the negator directly in front: 안 가요, 못 마셔요.
Are 아니요 and 아니에요 the same word? Close cousins with different jobs. 아니요 is the stand-alone answer “no”: 학생이에요? — 아니요. 아니에요 is a verb meaning “is not” and needs a noun with 이/가 in front: 학생이 아니에요 = I am not a student. Bonus: Koreans also say 아니에요 to brush off thanks, like “not at all.”
Next: ordering food in Korean — 주세요 and -(으)세요. Previous: daily routine with 에서 and -고 있다. Full path: curriculum hub.