Cannot (Inability)

못: "can't", and why it isn't 안

못 is the particle of things getting in your way. Korean splits negation into two words where English only has one, and the split is about why the thing isn't happening.

안 is choice, 못 is obstacle

• 술을 안 마셔요. (sur-eul an masyeoyo) — "I don't drink." A decision.
• 술을 못 마셔요. (sur-eul mot masyeoyo) — "I can't drink." Something stops you: an allergy, medication, a low tolerance.

English says "I don't drink" for both and lets tone carry the rest. Korean makes you pick, and picking wrong changes what you told someone about yourself.

Where it goes

• Short form: 못 in front of the verb. 못 가요 (mot gayo), "I can't go."
• Long form: verb stem + 지 못하다. 가지 못해요 (gaji mothaeyo). More formal, more common in writing.

The 하다 trap. With 하다 verbs, 못 slips inside the word rather than sitting in front of it:

• 공부 못 해요. (gongbu mot haeyo) ✓ — "I can't study."
• 못 공부해요. ✗

The noun comes first, then 못, then 해요. This one catches nearly everyone at least once.

It doesn't work with adjectives

못 is about ability, and adjectives don't describe abilities. So:

• 못 예뻐요 ✗

If you want "not pretty", you need 안 예뻐요 (an yeppeoyo) or 예쁘지 않아요 (yeppeuji anayo). Reaching for 못 here is a reliable sign someone learned the word as "not" rather than as "can't".

How it actually sounds

못 is written with a ㅅ 받침 but pronounced [몯], and it assimilates hard against whatever follows. This is why you can know the word and still not catch it in speech.

• 못 해요 → sounds like [모태요] (motaeyo)
• 못 먹어요 → sounds like [몬머거요] (monmeogeoyo)
• 못 가요 → sounds like [몯까요] (motkkayo)

If you've been hearing 몬 and 모 in dramas and wondering what word that was, this is it.

못 vs 지 못하다 vs 없다

Three ways to say something can't happen, and they aren't interchangeable:

• 못 마셔요 — I'm unable to drink.
• 마시지 못해요 — same thing, more formal.
• 마실 수 없어요 (masil su eopseoyo) — there's no possibility of drinking. Often circumstantial rather than personal.

The ~(으)ㄹ 수 있다/없다 page covers that third one properly.