Korean Irregular Verbs: the Seven Classes Explained

What Are Korean Irregular Verbs?

A Korean irregular verb is a verb or adjective whose stem changes when an ending is added, in a way that the basic recipe (stem + 아요/어요) does not predict. A regular verb keeps its stem: 먹다 (to eat) gives 먹어요. An irregular verb changes it: 듣다 (to listen) gives 들어요, with ㄷ turning into ㄹ.

Two facts keep the topic in proportion. First, most Korean verbs are regular. In this site's 474-entry verb dictionary, 109 entries belong to the seven classes, which is about 23 percent, and the rest are regular or 하다 verbs. Second, irregular words are not random. Each class follows one rule that you can apply to every member, including words you have never met. The stem is the part left after you remove 다, so the stem of 덥다 is 덥. If you are new to stems, start with Korean verb conjugation.

What Are the Seven Irregular Classes?

The seven classes are named after the stem sound that changes. The grid below gives the trigger, the change and one example for each, and the cards after it name the pages you can open for every class.

Each class has a hub with its word list and a lesson with the rule worked out step by step.

• ㅂ Irregular. The biggest class, with 36 entries in the site's dictionary. The ㅂ turns into 우 before a vowel, so 덥다 becomes 더워요, with the 와 exceptions 돕다 and 곱다. The lesson is Korean ㅂ irregular verbs and adjectives, and a sample word page is 줍다 conjugation.
• ㄷ Irregular. A small class of very common verbs: 듣다, 걷다 and 묻다 (to ask). The ㄷ becomes ㄹ before a vowel, and look-alikes such as 닫다 and 받다 stay regular. See 듣다 conjugation for every form.
• ㅅ Irregular. A tiny class with a clear rule: the ㅅ disappears before a vowel, as in 낫다, 짓다 and 붓다. Words like 웃다 and 씻다 look the same and are regular. A sample page is 붓다 (to pour).
• 르 Irregular. Very frequent words such as 모르다, 다르다 and 빠르다. The ㄹ doubles and the vowel is chosen by the earlier syllable. Open 모르다 conjugation for an example.
• ㅎ Irregular. The colour adjectives and the 그렇다 family: the ㅎ drops and the vowel becomes ㅐ, so 빨갛다 becomes 빨개요. See 그렇다 conjugation.
• ㅡ Irregular. The ㅡ-drop class: 쓰다, 크다, 바쁘다, 예쁘다 and 아프다. The earlier syllable decides between 아 and 어. A sample page is 쓰다 conjugation.
• ㄹ Irregular. The ㄹ-drop class: 살다, 알다, 만들다, 팔다 and 놀다. The ㄹ drops before ㄴ, ㅂ and ㅅ. A sample page is 팔다 conjugation.

Four supporting pages sit beside the classes. How to recognize irregular verbs is a decision tree that starts from the last letter of the stem. The irregular verbs chart compares all seven classes in one table. Regular verbs that look irregular explains why 입다, 받다, 웃다, 좋다 and 좁다 are regular. Rare Korean irregulars: 러 and 우 covers 이르다 → 이르러, 푸르다 → 푸르러 and 푸다 → 퍼요, with short rules and when to skip them. The first question after seeing the list is where to begin.

Which Irregular Class Should You Learn First?

Learn the ㅂ, 르 and ㅡ classes first, then ㄷ, ㅎ, ㄹ and ㅅ. This order is an editorial recommendation based on how many beginner words each class covers in the site's word list. The first three give you words such as 어렵다, 쉽다, 모르다, 다르다, 쓰다 and 아프다 within the first weeks.

1. ㅂ. The largest class, mostly adjectives that describe weather, taste and feeling: 덥다, 춥다, 맵다, 어렵다.
2. 르. Fourteen entries, including 모르다 (not know) and 다르다 (be different), which you will say daily.
3. ㅡ. Thirteen entries, including 쓰다, 크다, 아프다 and 바쁘다.
4. ㄷ. Six verbs, but 듣다 (listen) and 걷다 (walk) are very common.
5. ㅎ. Ten words, led by 그렇다 and the colours.
6. ㄹ. Twenty-six entries, including 살다, 알다 and 만들다, mostly met in formal and noun-modifying forms.
7. ㅅ. Four words, so it is the cheapest class to finish.

The ㄹ class is placed late because its change shows up only before ㄴ, ㅂ and ㅅ, such as 삽니다 and 사는. It is used constantly, but the polite present 살아요 looks regular, so errors appear later. Next, a distinction that saves time: where each rule applies.

Where Does Each Class Apply?

Each class changes before a different set of endings, and the set decides how many forms you must watch. ㅂ, ㄷ and ㅅ change before any ending that starts with a vowel. 르, ㅎ and ㅡ change only before 아 or 어. ㄹ changes before endings that start with ㄴ, ㅂ or ㅅ.

The practical effect: with a ㅂ, ㄷ, ㅅ or ㅎ word, the dictionary form is safe before consonants (덥고, 듣고, 낫고, 빨갛고), and it changes before vowels. With a 르 or ㅡ word, it changes only in the 아/어 forms: the polite present, the past, and -아서/어서. Knowing this cuts the number of forms you must check.

How Do You Recognize an Irregular Verb?

Look at the last letter of the stem, then test the verb against the class it might belong to. A stem ending in ㅂ, ㄷ, ㅅ, ㅎ, 르, ㅡ or ㄹ is a candidate, and the check is a short list of known members and regular look-alikes. The full decision tree is in how to recognize irregular verbs.

For example, the stem 듣 ends in ㄷ, so 듣다 is a candidate. It belongs to the short list of ㄷ irregular words, so it is irregular: 들어요. The stem 닫 also ends in ㄷ, but 닫다 is on the regular list: 닫아요. The final letter narrows the search, and the list decides.

Which Verbs Only Look Irregular?

Many verbs end in the same letters as irregular classes but stay regular. 입다 (to wear) ends in ㅂ and gives 입어요. 받다 (to receive) ends in ㄷ and gives 받아요. 웃다 (to laugh) ends in ㅅ and gives 웃어요. 좋다 (to be good) ends in ㅎ and gives 좋아요, with the ㅎ kept.

The list is learned word by word, with the help of regular verbs that look irregular. Another question learners ask concerns the label itself.

Is ㄹ Drop an Irregular?

The answer depends on the book. Korean school grammar (학교문법) treats the ㄹ drop and the ㅡ drop as regular conjugation, because they follow sound rules that apply to every stem of that shape. English-language learner materials often group them with the irregulars. This site teaches them as classes because a learner meets them in the same way: the polite-present recipe does not predict them.

Both views agree on the forms. 살다 is 삽니다 and 쓰다 is 써요 in every book, whichever label is used. If a Korean teacher says "ㄹ 탈락 is a regular rule", the statement is correct in school grammar, and it does not conflict with this site's grouping. To test any verb, use the Korean verb conjugator, and for a compact summary see the conjugation cheat sheet.

Korean irregular verbs are easiest when you take them one class at a time, with the rule first and the word list second. Pick a class above, or open the irregular verbs chart to see all seven side by side.

Frequently Asked Questions

Are all Korean verbs irregular? No. Most Korean verbs are regular, and 하다 verbs follow their own fixed pattern. In this site's 474-entry verb dictionary, 109 entries belong to the seven irregular classes, about 23 percent. The rest keep their stems, so the basic recipe of stem plus 아요 or 어요 works for them.

Is 입다 irregular? No. 입다 (to wear) ends in ㅂ, but it is regular: 입어요, 입었어요, 입으면. Only words on the ㅂ irregular list, such as 덥다 and 춥다, change ㅂ to 우. Adjectives ending in -ㅂ다 are usually irregular, while many action verbs, like 입다, 잡다 and 씹다, are regular.

Why do different books use different labels for irregular verbs? Korean school grammar counts the ㄹ drop and the ㅡ drop as regular sound rules and keeps the term irregular for ㅂ, ㄷ, ㅅ, 르 and ㅎ. Learner books often group all seven as irregular classes. The forms are the same in every book, so only the label differs.

Do irregular verbs change before every ending? No. Most irregular classes change only in front of certain sounds. ㅂ, ㄷ and ㅅ stems change before a vowel and stay intact before consonants, so 덥다 is 더워요 but 덥고. 르 and ㅡ stems change only before 아 or 어. ㄹ stems change before ㄴ, ㅂ and ㅅ.

Are 하다 verbs irregular? Not as a separate class. Verbs such as 공부하다 and 좋아하다 follow one fixed pattern, with 하 becoming 해 in the polite present: 공부해요. Korean school grammar calls this the 여 irregular (하여, shortened to 해), but the pattern never varies, so this site teaches it as its own pattern, not a class.