ㄷ irregular verbs (ㄷ 불규칙) are verbs whose stem ends in ㄷ and change this final ㄷ to ㄹ when followed by vowel-starting endings.
What Makes Them Irregular
Regular verbs maintain their stem throughout conjugation. ㄷ irregular verbs transform the final ㄷ to ㄹ before vowel-starting endings.
Rule
When ㄷ stem meets vowel-starting endings:
- ㄷ changes to ㄹ before vowel endings (-아/어, -으면, -을)
- ㄷ is kept before consonant-starting endings (-습니다, -지, -고)
Common ㄷ Irregular Verbs
Most ㄷ irregular verbs describe actions or states:
- 듣다 (deutda) - to hear, to listen
- 걷다 (geotda) - to walk
- 묻다 (mutda) - to ask
- 싣다 (sitda) - to load
- 깨닫다 (kkaedatda) - to realize
Conjugation Pattern
Pattern 1: ㄷ → ㄹ Before -어/아
듣다 (to hear):
- 듣 + 어요 → 들어요 (ㄷ → ㄹ)
- Stem ends with ㅡ, so uses -어
걷다 (to walk):
- 걷 + 어요 → 걸어요 (ㄷ → ㄹ)
- Stem ends with ㅓ, so uses -어
묻다 (to ask):
- 묻 + 어요 → 물어요 (ㄷ → ㄹ)
- Stem ends with ㅜ, so uses -어
깨닫다 (to realize):
- 깨닫 + 아요 → 깨달아요 (ㄷ → ㄹ)
- Stem ends with ㅏ, so uses -아
Pattern 2: ㄷ Kept Before Consonants
Before -습니다:
- 듣다 → 듣습니다 (listen - formal)
- 걷다 → 걷습니다 (walk - formal)
- 묻다 → 묻습니다 (ask - formal)
Before -지:
- 듣다 → 듣지 않아요 (don't listen)
- 걷다 → 걷지 마세요 (don't walk)
Before -고:
- 듣다 → 듣고 (listen and)
- 걷다 → 걷고 (walk and)
Pattern 3: ㄷ → ㄹ Before -(으)ㄴ/ㄹ
Modifiers -(으)ㄴ:
- 듣다 → 들은 (heard)
- 걷다 → 걸은 (walked)
- 묻다 → 물은 (asked)
Future modifier -(으)ㄹ:
- 듣다 → 들을 (will hear)
- 걷다 → 걸을 (will walk)
- 묻다 → 물을 (will ask)
Pattern 4: ㄷ → ㄹ Before -(으)면
Conditional:
- 듣다 → 들으면 (if hear)
- 걷다 → 걸으면 (if walk)
- 묻다 → 물으면 (if ask)
Full Conjugation Example: 듣다 (to hear/listen)
Informal Polite (-아/어요)
Present:
- 들어요 (hear/listen)
- 듣 + 어요 → 들어요
Past:
- 들었어요 (heard/listened)
- 듣 + 었어요 → 들었어요
Future:
- 들을 거예요 (will hear/listen)
- 듣 + 을 거예요 → 들을 거예요
Formal Polite (-습니다)
Present:
- 듣습니다 (hear/listen)
- ㄷ kept before consonant
Past:
- 들었습니다 (heard/listened)
- ㄷ → ㄹ before vowel
Future:
- 듣겠습니다 (will hear/listen)
- ㄷ kept before consonant
Connective Forms
-지만 (but):
- 듣지만 (although listen) - ㄷ kept
-아/어서 (so, because):
- 들어서 (because listen)
- ㄷ → ㄹ before vowel
-고 (and):
- 듣고 (listen and) - ㄷ kept
Modifiers
-(으)ㄴ (past descriptive):
- 들은 음악 (music that was heard)
- ㄷ → ㄹ
-(으)ㄹ (future/prospective):
- 들을 이야기 (story that will be heard)
- ㄷ → ㄹ
Full Conjugation Example: 걷다 (to walk)
Informal Polite
Present:
- 걸어요 (walk)
- 걷 + 어요 → 걸어요
Past:
- 걸었어요 (walked)
- 걷 + 었어요 → 걸었어요
Future:
- 걸을 거예요 (will walk)
- 걷 + 을 거예요 → 걸을 거예요
Formal Polite
Present:
- 걷습니다 (walk)
- ㄷ kept
Past:
- 걸었습니다 (walked)
- ㄷ → ㄹ
Future:
- 걷겠습니다 (will walk)
- ㄷ kept
Other Forms
-고 싶다:
- 걷고 싶어요 (want to walk) - ㄷ kept
-지 않다:
- 걷지 않아요 (don't walk) - ㄷ kept
-(으)면:
- 걸으면 (if walk) - ㄷ → ㄹ
Full Conjugation Example: 묻다 (to ask)
Informal Polite
Present:
- 물어요 (ask)
- 묻 + 어요 → 물어요
Past:
- 물었어요 (asked)
- 묻 + 었어요 → 물었어요
Future:
- 물을 거예요 (will ask)
- 묻 + 을 거예요 → 물을 거예요
Formal Polite
Present:
- 묻습니다 (ask)
Past:
- 물었습니다 (asked)
Future:
- 묻겠습니다 (will ask)
Imperative
-으세요:
- 물으세요 (please ask)
- ㄷ → ㄹ before vowel
Common Expressions
듣다 (to hear/listen)
- 들어요 (hear/listen)
- 들었어요? (Did you hear?)
- 음악을 들어요 (listen to music)
- 이야기를 들었어요 (heard the story)
걷다 (to walk)
- 걸어요 (walk)
- 걸어서 가요 (go by walking)
- 공원을 걸었어요 (walked in the park)
- 천천히 걸으세요 (please walk slowly)
묻다 (to ask)
- 물어요 (ask)
- 물어봐요 (ask - with 보다)
- 질문을 물었어요 (asked a question)
- 물어보세요 (please ask)
싣다 (to load)
- 실어요 (load)
- 짐을 실었어요 (loaded the luggage)
깨닫다 (to realize)
- 깨달아요 (realize)
- 깨달았어요 (realized)
- 진실을 깨달았어요 (realized the truth)
With Different Endings
-(으)ㄹ 거예요 (future)
ㄷ → ㄹ before ㄹ:
- 듣다 → 들을 거예요 (will hear)
- 걷다 → 걸을 거예요 (will walk)
- 묻다 → 물을 거예요 (will ask)
-(으)면 (if/when)
ㄷ → ㄹ before vowel:
- 듣다 → 들으면 (if hear)
- 걷다 → 걸으면 (if walk)
- 묻다 → 물으면 (if ask)
-지 않다 (negative)
ㄷ kept before 지:
- 듣다 → 듣지 않아요 (don't hear)
- 걷다 → 걷지 않아요 (don't walk)
- 묻다 → 묻지 않아요 (don't ask)
-고 싶다 (want to)
ㄷ kept before 고:
- 듣다 → 듣고 싶어요 (want to hear)
- 걷다 → 걷고 싶어요 (want to walk)
- 묻다 → 묻고 싶어요 (want to ask)
-아/어서 (because)
ㄷ → ㄹ before vowel:
- 듣다 → 들어서 (because hear)
- 걷다 → 걸어서 (because walk)
- 묻다 → 물어서 (because ask)
-고 (and)
ㄷ kept before 고:
- 듣다 → 듣고 (hear and)
- 걷다 → 걷고 (walk and)
- 묻다 → 묻고 (ask and)
In Modifiers
Past -(으)ㄴ:
- 듣다 → 들은 (heard)
- 걷다 → 걸은 (walked)
- 묻다 → 물은 (asked)
Future -(으)ㄹ:
- 듣다 → 들을 (will hear)
- 걷다 → 걸을 (will walk)
- 묻다 → 물을 (will ask)
Examples:
- 들은 이야기 (story that was heard)
- 걸은 길 (road that was walked)
- 물을 사람 (person who will ask)
Identifying ㄷ Irregular Verbs
Check if stem ends in ㄷ:
- 듣다 → stem: 듣 (ends in ㄷ) ✓
- 걷다 → stem: 걷 (ends in ㄷ) ✓
- 묻다 → stem: 묻 (ends in ㄷ) ✓
Not all ㄷ verbs are irregular.
Exceptions: Regular ㄷ Verbs
These follow regular conjugation:
- 받다 (batda) - to receive → 받아요 (not 발아요)
- 믿다 (mitda) - to believe → 믿어요 (not 밀어요)
- 닫다 (datda) - to close → 닫아요 (not 달아요)
Test: If conjugated form has ㄹ appearing (들어요, 걸어요), it's irregular. If ㄷ stays (받아요, 믿어요), it's regular.
Another ㄷ Verb: 묻다 (to bury)
There's a homophone of 묻다 (to ask):
- 묻다 (mutda) - to bury → 묻어요 (regular!)
This is a different verb and follows regular conjugation:
- 묻다 (to bury) → 묻어요 (not 물어요)
- 묻다 (to ask) → 물어요 (irregular)
Context determines which 묻다 is being used.
Common Patterns in Sentences
Listening:
- 음악을 들어요. (I listen to music.)
- 소식을 들었어요. (I heard the news.)
Walking:
- 공원에서 걸어요. (I walk in the park.)
- 집까지 걸었어요. (I walked home.)
Asking:
- 선생님께 물어요. (I ask the teacher.)
- 친구한테 물었어요. (I asked my friend.)
Realizing:
- 진실을 깨달았어요. (I realized the truth.)
- 실수를 깨닫고 있어요. (I'm realizing the mistake.)
Summary of Changes
Before vowel endings (-어/아, -으면, -을):
- ㄷ → ㄹ
- 듣다 → 들어요, 들으면, 들을
- 걷다 → 걸어요, 걸으면, 걸을
Before consonant endings (-습니다, -지, -고, -겠):
- ㄷ stays
- 듣다 → 듣습니다, 듣지, 듣고
- 걷다 → 걷습니다, 걷지, 걷고
Key Points
- ✅ ㄷ becomes ㄹ before vowel endings
- ✅ ㄷ stays before consonant endings
- ✅ Common verbs: 듣다, 걷다, 묻다 (ask), 싣다
- ✅ Check: 받다, 믿다, 닫다 are regular
- ✅ Test method: look for ㄹ appearing in conjugation
- ✅ Pattern: 듣다→들어요, 걷다→걸어요
Understanding ㄷ irregular verbs is important for common daily actions like listening, walking, and asking questions.