What Are Irregular Conjugations?
Most Korean verbs and adjectives follow predictable conjugation rules. When you add an ending like -아요/어요 , you can usually guess the result.
However, some verbs and adjectives have stems that change in unexpected ways. This usually happens when the stem meets an ending that starts with a vowel.
These are called irregular conjugations (불규칙 활용). They aren't random; they follow their own special patterns. This lesson will introduce you to some of the most common ones you'll see as a beginner.
The 'ㅂ' Irregular (ㅂ 불규칙)
This is a very common pattern, especially with descriptive verbs (adjectives).
The Rule
When a verb or adjective stem ends in ㅂ and is followed by a vowel (like in -아요/어요 ), the ㅂ is dropped and 우 is added to the stem. This 우 then combines with the following vowel.
우 + 어요 becomes 워요
우 + 아요 becomes 와요
Examples
Dictionary Form · Stem · Conjugation · Result
덥다 · 덥 · 덥 + 어요 → 더 + 우 + 어요 · 더워요
춥다 · 춥 · 춥 + 어요 → 추 + 우 + 어요 · 추워요
어렵다 · 어렵 · 어렵 + 어요 → 어려 + 우 + 어요 · 어려워요
Special Exceptions: 돕다 & 곱다
For 돕다 (to help) and 곱다 (to be beautiful/fine), the ㅂ changes to 오 instead of 우 .
돕다 → 돕 + 아요 → 도 + 오 + 아요 → 도와요
Watch out for regular verbs! Not all verbs ending in ㅂ are irregular. Words like 입다 (to wear) and 잡다 (to catch) conjugate normally: 입어요 , 잡아요 .
The 'ㄷ' Irregular (ㄷ 불규칙)
This pattern applies to several common action verbs.
The Rule
When a verb stem ends in ㄷ and is followed by a vowel, the ㄷ changes to ㄹ .
Examples
Dictionary Form · Stem · Conjugation · Result
듣다 · 듣 · 듣 + 어요 → 들 + 어요 · 들어요
걷다 · 걷 · 걷 + 어요 → 걸 + 어요 · 걸어요
묻다 · 묻 · 묻 + 어요 → 물 + 어요 · 물어요
Watch out for regular verbs! Some common verbs like 닫다 (to close) and 믿다 (to believe) are regular and keep the ㄷ : 닫아요 , 믿어요 .
The '르' and '으' Irregulars (르/으 불규칙)
These two irregular patterns involve changes to the final vowel of the stem.
The '르' Irregular (르 불규칙)
When a stem ends in 르 and is followed by -아요/어요 :
An extra ㄹ is added as the final consonant of the preceding syllable.
The 르 itself changes to 라 or 러 based on vowel harmony.
Dictionary Form · Conjugation · Result
모르다 · 모 + ㄹ + 아요 · 몰라요
부르다 (to call/sing) · 부 + ㄹ + 어요 · 불러요
빠르다 · 빠 + ㄹ + 아요 · 빨라요
The '으' Irregular (으 불규칙)
When a stem ends in 으 and is followed by -아요/어요 , the 으 vowel is simply dropped. You then choose between -아요 or -어요 based on the last vowel of the remaining stem .
쓰다 (to write): Stem is 쓰 . Drop 으 → ㅆ . There's no preceding vowel, so we default to -어요 → 써요 .
아프다 (to be sick/hurt): Stem is 아프 . Drop 으 → 아ㅍ . The last vowel is 아 , so we add -아요 → 아파요 .
예쁘다 (to be pretty): Stem is 예쁘 . Drop 으 → 예ㅃ . The last vowel is 에 (not 아 or 오 ), so we add -어요 → 예뻐요 .
Quick review
르 불규칙: 모르다 -> 몰라요
으 불규칙: 쓰다 -> 써요, 아프다 -> 아파요