ㅂ irregular verbs (ㅂ 불규칙) are verbs and adjectives whose stem ends in ㅂ and change this final ㅂ to 우 (u) or 오 (o) when followed by vowel-starting endings.
What Makes Them Irregular
Regular verbs maintain their stem throughout conjugation. ㅂ irregular verbs transform the final ㅂ before vowel-starting endings.
Rule
When ㅂ stem meets vowel-starting endings:
- ㅂ changes to 우 before endings starting with -어
- ㅂ changes to 오 before endings starting with -아
- ㅂ is kept before consonant-starting endings
Common ㅂ Irregular Verbs
Adjectives (Most ㅂ irregular words)
- 춥다 (chupda) - to be cold
- 덥다 (deopda) - to be hot
- 아름답다 (areumdapda) - to be beautiful
- 즐겁다 (jeulgeopda) - to be joyful/fun
- 반갑다 (bangapda) - to be glad/nice to meet
- 무섭다 (museopda) - to be scary
- 어렵다 (eoryeopda) - to be difficult
- 쉽다 (swipda) - to be easy
- 가볍다 (gabyeopda) - to be light (weight)
- 무겁다 (mugeopda) - to be heavy
- 귀엽다 (gwiyeopda) - to be cute
- 고맙다 (gomapda) - to be thankful
Verbs (Fewer)
- 돕다 (dopda) - to help
- 줍다 (jupda) - to pick up
Conjugation Pattern
Pattern 1: ㅂ → 우 Before -어
When stem vowel is ㅗ or ㅜ (dark vowels), or neutral:
춥다 (to be cold):
- 춥 + 어요 → 추우어요 → 추워요
- ㅂ drops, 우 is added
- 우 + 어 contracts to 워
돕다 (to help):
- 돕 + 어요 → 도우어요 → 도와요
- ㅂ drops, 우 is added
- 우 + 어 contracts to 와
무겁다 (to be heavy):
- 무겁 + 어요 → 무거우어요 → 무거워요
- ㅂ drops, 우 is added
- 우 + 어 contracts to 워
Pattern 2: ㅂ → 오 Before -아 (Rare)
This pattern is less common because most ㅂ irregular verbs take -어.
곱다 (to be beautiful/fair - archaic):
- 곱 + 아요 → 고오아요 → 고와요
Generally, the -어 pattern (becoming 워 or 와) is what you'll encounter most.
Pattern 3: ㅂ Kept Before Consonants
Before -습니다:
- 춥다 → 춥습니다 (is cold - formal)
- 덥다 → 덥습니다 (is hot - formal)
- 돕다 → 돕습니다 (help - formal)
Before -네요:
- 춥다 → 춥네요 (it's cold!)
- 덥다 → 덥네요 (it's hot!)
Before -지만:
- 춥다 → 춥지만 (although cold)
- 쉽다 → 쉽지만 (although easy)
Full Conjugation Example: 춥다 (to be cold)
Informal Polite (-아/어요)
Present:
- 추워요 (is cold)
- 춥 + 어요 → 추우어요 → 추워요
Past:
- 추웠어요 (was cold)
- 춥 + 었어요 → 추우었어요 → 추웠어요
Future:
- 추울 거예요 (will be cold)
- 춥 + ㄹ 거예요 → 추울 거예요 (ㅂ drops before ㄹ)
Formal Polite (-습니다)
Present:
- 춥습니다 (is cold)
- ㅂ kept before consonant
Past:
- 추웠습니다 (was cold)
- 춥 + 었습니다 → 추우었습니다 → 추웠습니다
Future:
- 춥겠습니다 (will be cold)
- ㅂ kept before consonant
Connective Forms
-지만 (but):
- 춥지만 (although cold) - ㅂ kept
-아/어서 (so, because):
- 추워서 (because cold)
- 춥 + 어서 → 추우어서 → 추워서
-고 (and):
- 춥고 (is cold and) - ㅂ kept
Modifiers
-(으)ㄴ (descriptive):
- 추운 (cold)
- 춥 + 은 → 추운 (ㅂ drops before ㄴ)
Full Conjugation Example: 돕다 (to help)
Informal Polite
Present:
- 도와요 (help)
- 돕 + 어요 → 도우어요 → 도와요
Past:
- 도왔어요 (helped)
- 돕 + 었어요 → 도우었어요 → 도왔어요
Future:
- 도울 거예요 (will help)
- 돕 + ㄹ 거예요 → 도울 거예요
Formal Polite
Present:
- 돕습니다 (help)
- ㅂ kept
Past:
- 도왔습니다 (helped)
Future:
- 돕겠습니다 (will help)
- ㅂ kept
Other Forms
-고 싶다:
- 돕고 싶어요 (want to help) - ㅂ kept
-지 않다:
- 돕지 않아요 (don't help) - ㅂ kept
-(으)면:
- 도우면 (if help)
- 돕 + 으면 → 도우면
Contraction Rules
When ㅂ becomes 우 before -어 endings, contractions occur:
우 + 어 → 워:
- 춥 + 어요 → 추우어요 → 추워요
- 쉽 + 어요 → 쉬우어요 → 쉬워요
- 무겁 + 어요 → 무거우어요 → 무거워요
우 + 어 → 와 (when stem ends in ㅗ):
- 돕 + 어요 → 도우어요 → 도와요
- 곱 + 어요 → 고우어요 → 고와요
The contraction happens automatically in natural speech.
Common Expressions
춥다 (to be cold)
- 추워요 (it's cold)
- 추웠어요 (it was cold)
- 추운 날씨 (cold weather)
- 추워서 (because it's cold)
덥다 (to be hot)
- 더워요 (it's hot)
- 더웠어요 (it was hot)
- 더운 여름 (hot summer)
- 더워서 (because it's hot)
아름답다 (to be beautiful)
- 아름다워요 (is beautiful)
- 아름다웠어요 (was beautiful)
- 아름다운 꽃 (beautiful flower)
반갑다 (to be glad to meet)
- 반가워요 (nice to meet you / glad to see you)
- 반가웠어요 (was glad)
- 반갑습니다 (nice to meet you - formal)
돕다 (to help)
- 도와요 (help)
- 도와주세요 (please help)
- 도왔어요 (helped)
With Different Endings
-(으)ㄹ 거예요 (future)
ㅂ drops before ㄹ:
- 춥다 → 추울 거예요 (will be cold)
- 덥다 → 더울 거예요 (will be hot)
- 돕다 → 도울 거예요 (will help)
-(으)면 (if/when)
ㅂ becomes 우 before 으:
- 춥다 → 추우면 (if cold)
- 덥다 → 더우면 (if hot)
- 돕다 → 도우면 (if help)
-지 않다 (negative)
ㅂ kept before 지:
- 춥다 → 춥지 않아요 (not cold)
- 덥다 → 덥지 않아요 (not hot)
- 돕다 → 돕지 않아요 (don't help)
-고 싶다 (want to)
ㅂ kept before 고:
- 돕다 → 돕고 싶어요 (want to help)
-아/어서 (because)
ㅂ becomes 우, contracts with 어:
- 춥다 → 추워서 (because cold)
- 덥다 → 더워서 (because hot)
- 돕다 → 도와서 (because help)
In Modifiers
Present/Descriptive -(으)ㄴ:
- 춥다 → 추운 (cold)
- 덥다 → 더운 (hot)
- 쉽다 → 쉬운 (easy)
- 어렵다 → 어려운 (difficult)
- 아름답다 → 아름다운 (beautiful)
- 무겁다 → 무거운 (heavy)
Adverbial -게:
- 쉽다 → 쉽게 (easily) - ㅂ kept
- 아름답다 → 아름답게 (beautifully) - ㅂ kept
Identifying ㅂ Irregular Verbs
Check if stem ends in ㅂ:
- 춥다 → stem: 춥 (ends in ㅂ) ✓
- 돕다 → stem: 돕 (ends in ㅂ) ✓
Most ㅂ final adjectives are irregular Most ㅂ final verbs are regular (입다 to wear, 잡다 to catch)
Exceptions: Regular ㅂ Verbs/Adjectives
These follow regular conjugation:
- 입다 (ipda) - to wear → 입어요 (not 이워요)
- 잡다 (japda) - to catch → 잡아요 (not 자와요)
- 좁다 (jopda) - to be narrow → 좁아요 (not 조와요)
To check: if it conjugates with a 우/오 appearing, it's irregular.
Common Patterns in Sentences
Weather:
- 날씨가 추워요. (The weather is cold.)
- 여름이 더워요. (Summer is hot.)
Descriptions:
- 꽃이 아름다워요. (The flower is beautiful.)
- 숙제가 어려워요. (Homework is difficult.)
Actions:
- 저를 도와주세요. (Please help me.)
- 친구를 도왔어요. (I helped my friend.)
Greetings:
- 만나서 반가워요. (Nice to meet you. / Glad to meet you.)
- 다시 만나서 반가웠어요. (Was glad to see you again.)
Summary of Changes
Before vowel endings (-어/아):
- ㅂ → 우 → contracts to 워 or 와
- 춥다 → 추워요
- 돕다 → 도와요
Before consonant endings (-습니다, -지, -고):
- ㅂ stays
- 춥다 → 춥습니다
- 돕다 → 돕지만
Before -(으)ㄴ, -(으)ㄹ:
- ㅂ drops, 우 is inserted
- 춥다 → 추운
- 돕다 → 도울
Key Points
- ✅ ㅂ becomes 우 before vowel endings
- ✅ 우 + 어 contracts to 워 or 와
- ✅ ㅂ stays before consonant endings
- ✅ Most ㅂ irregular words are adjectives
- ✅ Common pattern: 춥다→추워요, 덥다→더워요
- ✅ Check: 입다, 잡다 are regular despite ㅂ ending
Understanding ㅂ irregular conjugation is crucial for describing weather, emotions, and physical states, as many common descriptive words follow this pattern.