Korean Irregular Verbs: ㅡ, ㅂ, and 르 Irregulars Explained

You've learned the rules for conjugating Korean verbs. Remove 다, check the last vowel, add 아요 or 어요.

It works - until you hit verbs like these:

쓰다 → ✅ 써요 (not 쓰어요) 덥다 → ✅ 더워요 (not 덥아요) 모르다 → ✅ 몰라요 (not 모르아요)

These are irregular verbs - verbs that don't follow the standard conjugation rules. Korean has several types, but three are essential for beginners: ㅡ irregular, ㅂ irregular, and 르 irregular.

This post covers all three - present tense, past tense, and the verbs you're most likely to encounter.

Why Irregular Verbs Exist

Korean verbs become irregular when two vowels would otherwise collide in an awkward or unnatural way. The irregularity is the language's way of making pronunciation smoother.

Once you understand the pattern behind each type, they stop feeling random and start feeling logical.

1. ㅡ Irregular (으 탈락)

The Rule

When the verb stem ends in ㅡ and you add 아요/어요, the ㅡ drops - then the vowel rule applies to the syllable before it.

Step 1: Remove ㅡ from the stem Step 2: Check the vowel of the syllable that's now last Step 3: Add 아요 (if ㅏ/ㅗ) or 어요 (everything else)

Common ㅡ Irregular Verbs

💡 When ㅡ is the very first (and only) vowel - like 쓰다, 크다 - the ㅡ drops and 어요 attaches directly: 쓰 → 써요, 크 → 커요.

ㅡ Irregular in Real Sentences

요즘 너무 바빠요.

• Natural: I'm so busy these days.

머리가 아파요.

• Natural: I have a headache. / My head hurts.

꽃이 정말 예뻐요.

• Natural: The flowers are really pretty.

불을 꺼요.

• Natural: I turn off the light.

지난주에 너무 바빴어요.

• Natural: I was so busy last week.

2. ㅂ Irregular (ㅂ 불규칙)

The Rule

When the verb stem ends in ㅂ and you add a vowel ending, the ㅂ changes to 우 - then 어요 attaches, contracting to 워요.

ㅂ → 우 + 어요 = 워요

One exception: 돕다 (to help) and 곱다 (beautiful) → ㅂ changes to 오 → 와요 (not 워요).

Common ㅂ Irregular Verbs

⚠️ Regular ㅂ verbs do exist - verbs ending in ㅂ that don't change. The most common: 입다 (wear) → 입어요 ✅ (regular) 잡다 (grab) → 잡아요 ✅ (regular) 씹다 (chew) → 씹어요 ✅ (regular)

Unfortunately there's no shortcut to knowing which ones are irregular - you learn them as vocabulary.

ㅂ Irregular in Real Sentences

오늘 날씨가 너무 더워요.

• Natural: The weather is so hot today.

한국어가 어렵지만 재미있어요.

• Natural: Korean is difficult but interesting.

이 가방 너무 무거워요!

• Natural: This bag is so heavy!

그 영화 무서웠어요?

• Natural: Was that movie scary?

강아지가 너무 귀여워요.

• Natural: The puppy is so cute.

지난겨울은 정말 추웠어요.

• Natural: Last winter was really cold.

3. 르 Irregular (르 불규칙)

The Rule

When the verb stem ends in 르 and you add 아요/어요, the 르 splits: ㄹ moves down as a 받침 to the syllable before it, and 아요/어요 attaches.

모르다 → 모르 + 아요 → 몰 + 라요 = 몰라요 부르다 → 부르 + 어요 → 불 + 러요 = 불러요

The pattern: 르 → ㄹ (받침) + 라요/러요

• If the vowel before 르 is ㅏ or ㅗ → ㄹ라요
• Everything else → ㄹ러요

Common 르 Irregular Verbs

르 Irregular in Real Sentences

그 단어 몰라요.

• Natural: I don't know that word.

이 노래 불러요.

• Natural: I'm singing this song.

이것과 저것이 달라요.

• Natural: This and that are different.

KTX가 정말 빨라요.

• Natural: The KTX is really fast.

가위로 잘라요.

• Natural: I cut it with scissors.

그때는 몰랐어요.

• Natural: I didn't know at that time.

All Three Together: Side-by-Side

Real Conversation Using All Three

📍 Talking about the weather and daily life

A: 오늘 날씨 어때요? (How's the weather today?)

B: 너무 더워요. 어제보다 더 더운 것 같아요. (It's so hot. I think it's hotter than yesterday.)

A: 맞아요. 저는 더위를 너무 싫어해요. 빨리 가을이 됐으면 좋겠어요. (Right. I really hate the heat. I wish autumn would come quickly.)

B: 저도요. 그런데 가을 날씨를 잘 몰라요. 한국에 처음 왔어요. (Me too. But I don't know what autumn weather is like. I came to Korea for the first time.)

A: 한국 가을은 정말 아름다워요. 단풍이 예뻐요. (Korean autumn is really beautiful. The fall foliage is pretty.)

Quick Practice

Conjugate into present tense (-아요/어요):

1. 슬프다 (sad) → ㅡ irregular
2. 가볍다 (light) → ㅂ irregular
3. 빠르다 (fast) → 르 irregular
4. 예쁘다 (pretty) → ㅡ irregular
5. 다르다 (different) → 르 irregular
6. 무섭다 (scary) → ㅂ irregular

Answers:

1. 슬퍼요
2. 가벼워요
3. 빨라요
4. 예뻐요
5. 달라요
6. 무서워요

Summary

Irregular verbs can feel like obstacles at first - but they're also some of the most frequently used verbs in Korean. Once you know 더워요, 몰라요, 바빠요, and 어려워요 by heart, you'll realize you're already using them every day without even thinking about it.

📚 This Is Chapter 8 of the A1 Masterclass

ㅂ, ㅡ, and 르 irregular verbs are covered in Chapter 8: 어제는 날씨가 더웠어요 of the Today Korean A1 Masterclass - introduced in the context of weather, feelings, and past experiences so they're learned the way they're actually used.

👉 See the full A1 curriculum