At a glance
- Before a vowel, the final ㅅ drops: 낫 + 아요 = 나아요.
- Before a consonant, the ㅅ stays: 낫고, 낫습니다.
- Regular look-alikes: 웃다, 씻다, 벗다.
- One lesson explains the rule in about 30 minutes.
The next section states the rule once, in one paragraph, so that the lists below make sense.
What Is ㅅ Irregular?
The ㅅ irregular (ㅅ 불규칙) is a conjugation class in which a stem that ends in ㅅ loses that ㅅ before an ending that begins with a vowel. A stem (어간) is the verb without its final 다, and an ending (어미) is the part added to it. For 낫다 the stem is 낫, and 낫 + 아요 gives 나아요, not 낫아요.
The ㅅ stays when the ending starts with a consonant: 낫고 ("recover and"), 낫습니다 ("recovers", formal). The linking vowel 으 in endings such as -(으)면 counts as a vowel, so the ㅅ drops there too: 나으면 ("if [it] gets better").
Compare a regular verb. 웃다 keeps its ㅅ everywhere: 웃어요, 웃으면, 웃고. Only the closed list below drops it. The ㅅ irregular lesson walks through the rule with step-by-step examples, past forms and audio. This section sits inside the wider set of classes explained in Korean irregular verbs. The next section lists the members.
The ㅅ-Irregular Verb List
The ㅅ irregular is a closed list of about six verbs. The table gives each verb with its polite present and a one-line sense. The first four link to their own dictionary pages with every form and audio.
| Verb | Meaning | Polite present | Polite past | Dictionary page |
|---|---|---|---|---|
| 낫다 | to recover; to be better | 나아요 | 나았어요 | natda conjugation |
| 짓다 | to build; to make (a name, a meal) | 지어요 | 지었어요 | jitda conjugation |
| 붓다 | to pour; to swell | 부어요 | 부었어요 | pour in korean |
| 잇다 | to connect; to link | 이어요 | 이었어요 | connect in korean |
| 긋다 | to draw (a line) | 그어요 | 그었어요 | no separate page |
| 젓다 | to stir | 저어요 | 저었어요 | no separate page |
Most learners need only 낫다 and 짓다 early. 감기가 나았어요 ("My cold got better") and 집을 지어요 ("[Someone] builds a house") are typical sentences. 붓다 appears in cooking, where it means "pour": see 붓다 in Korean cooking verbs. The forms were cross-checked with the site's conjugation engine. The next section covers the verbs that cause the opposite mistake.
Which ㅅ Verbs Are Regular?
Many verbs end in ㅅ and keep it, so the written dictionary form gives no clue about the class. The test is to form the polite present: if the ㅅ is still there, the verb is regular.
| Verb | Meaning | Polite present | Class |
|---|---|---|---|
| 웃다 | to laugh, to smile | 웃어요 | regular |
| 씻다 | to wash | 씻어요 | regular |
| 벗다 | to take off | 벗어요 | regular |
| 빼앗다 | to take away by force | 빼앗아요 | regular |
| 솟다 | to rise up | 솟아요 | regular |
The lesson on regular verbs that look irregular compares these pairs with the irregular verbs in more detail. The next section covers two pairs of words that sound alike.
Words That Sound Alike
Two ㅅ-irregular verbs have regular sound-alikes. 낫다 and 낮다 are both [낟따] in the dictionary form, and 붓다 and 붙다 are both [붇따]. The spelling and the class differ, so each pair needs a check.
| Pair | Meaning | Polite present | Class |
|---|---|---|---|
| 낫다 | to recover | 나아요 | ㅅ irregular |
| 낮다 | to be low | 낮아요 | regular |
| 붓다 | to pour; to swell | 부어요 | ㅅ irregular |
| 붙다 | to stick | 붙어요 | regular |
In speech, 나아요 has a vowel break [나아요], while 낮아요 sounds like [나자요]. A third sound-alike, 낳다 (to give birth), is regular, yet its polite present 낳아요 is also said [나아요], because ㅎ is silent before a vowel. The lesson explains this with audio. The next section turns the page into a plan.
Learn the ㅅ Irregular: Where Should You Start?
Start with the lesson, then use the dictionary pages for forms you need. The ㅅ irregular is small: this site's verb dictionary list has 474 entries, and 4 of them are ㅅ irregular. By comparison, 36 are ㅂ irregular and 14 are 르 irregular. This count describes the site's word list, not how often the words appear in speech.
| If you want to... | Read | What you get |
|---|---|---|
| learn the rule and the past forms | Korean ㅅ Irregular Explained | rule, closed list, 낫다 vs 낮다, pronunciation, 8-question practice |
| check a verb that might be regular | regular verbs that look irregular | side-by-side pairs of irregular and regular verbs |
| see every form of one verb | the dictionary pages in the list above | forms, examples and audio per verb |
| compare all seven classes | Korean irregular verbs | the class grid and the recognition lesson |
Korean ㅅ Irregular Explained
The lesson teaches the ㅅ-drop in 30 minutes. You finish able to conjugate 낫다 and 짓다 in the polite present, past and future, and to tell them from 웃다, 씻다 and 낮다. It includes audio for the two-vowel pronunciation of 나아요 and 지어요.
What this page does not cover. It lists the class but does not conjugate every verb in every speech level. The lesson and the dictionary pages do that. About this page. Last updated 2026-10-09. The Korean text and spoken forms on this page were machine-generated and reviewed and signed off by Min-ji Park on 15 October 2026. Forms were cross-checked with the site's rule-based conjugation engine. Romanization follows the Revised Romanization of Korean and is shown only as a learning aid.
Frequently Asked Questions
What is ㅅ irregular? The ㅅ irregular is a conjugation class in which a stem-final ㅅ is deleted before an ending that starts with a vowel. 낫다 becomes 나아요 and 짓다 becomes 지어요. Before a consonant the ㅅ stays, as in 낫고 and 짓습니다. The class is a short, closed list of verbs, so new words do not join it.
Is 웃다 irregular? No. 웃다 ("to laugh, to smile") keeps its ㅅ before every ending: 웃어요, 웃었어요, 웃으면. It is a regular verb that only looks like 낫다 on the page. To check any ㅅ verb, form the polite present. If the ㅅ is still there, as in 웃어요, the verb is regular.
How is 낫다 different from 낮다? 낫다 means "to recover" and is a ㅅ-irregular verb: 나아요. 낮다 means "to be low" and is a regular adjective: 낮아요. Both are pronounced [낟따] in the dictionary form, so they are homophones. In the polite present they split: 나아요 has a vowel break, while 낮아요 sounds like [나자요].
How many ㅅ verbs are there? The ㅅ irregular is a closed list of about six verbs: 낫다, 짓다, 붓다, 잇다, 긋다 and 젓다. This site has dictionary pages for the first four. Many other Korean verbs end in ㅅ, such as 웃다, 씻다 and 벗다, but they are regular and keep the ㅅ.