-(으)므로 is a formal connective meaning "because," "since," "therefore," or "as." It expresses reason or cause in formal, written, or official contexts.
Structure
Verb/Adjective stem + -(으)므로
Breakdown:
- -(으)므로: Formal causal connective
- Used primarily in writing or formal speech
- More formal than -아/어서 or -니까
Literal meaning: "Because/since [statement]"
Formation Rules
No Final Consonant: -므로
Stems ending in vowel:
- 가다 → 가므로 (because [I/one] go)
- 크다 → 크므로 (because it's big)
- 하다 → 하므로 (because [I/one] do)
- 되다 → 되므로 (because it becomes)
With Final Consonant: -으므로
Stems ending in consonant:
- 먹다 → 먹으므로 (because [I/one] eat)
- 좋다 → 좋으므로 (because it's good)
- 많다 → 많으므로 (because there are many)
- 작다 → 작으므로 (because it's small)
ᄅ Irregular
Stems ending in ᄅ drop the ᄅ before 으:
- 살다 → 사므로 (because [I/one] live)
- 만들다 → 만드므로 (because [I/one] make)
- 알다 → 아므로 (because [I/one] know)
With 이다
Noun + (이)므로:
With final consonant: 이므로
- 학생이므로 (because [one is] a student)
- 사실이므로 (because it's a fact)
No final consonant: 므로
- 선생님이므로 → 선생이므로 (because [one is] a teacher)
Core Meaning: Formal Reason
Stating Reasons Formally
Explaining cause in formal contexts:
- 비가 오므로 우산을 가져가십시오 (Because it's raining, please take an umbrella)
- 중요하므로 주의하시기 바랍니다 (Because it's important, please be careful)
- 위험하므로 접근하지 마십시오 (Because it's dangerous, do not approach)
Logical Conclusions
Drawing formal conclusions:
- 증거가 없으므로 무죄입니다 (Because there's no evidence, [they are] innocent)
- 규칙이므로 따라야 합니다 (Because it's a rule, you must follow it)
- 사실이므로 믿으셔도 됩니다 (Because it's a fact, you may believe it)
Common Usage Patterns
Official Notices
Formal announcements:
- 공사 중이므로 우회하십시오 (Because construction is ongoing, please detour)
- 휴일이므로 영업하지 않습니다 (Because it's a holiday, we're not open)
- 만석이므로 예약이 필요합니다 (Because it's full, reservation is needed)
Written Explanations
Formal writing:
- 이러한 이유로 인하므로 (because of this reason)
- 법으로 정해져 있으므로 (because it's established by law)
- 연구 결과 밝혀졌으므로 (because research revealed)
Rules and Regulations
Official rules:
- 금지되어 있으므로 (because it's prohibited)
- 허가가 필요하므로 (because permission is needed)
- 의무이므로 (because it's obligatory)
Formal Register
Extremely Formal
Characteristics:
- Primarily written Korean
- Official documents
- Formal speeches
- News reports
- Academic writing
- Legal documents
Less common in:
- Casual conversation
- Daily speech
- Informal writing
Politeness Levels
Always Formal Context
Used with formal endings:
- 중요하므로 주의하십시오 (formal command)
- 사실이므로 믿으셔도 됩니다 (formal permission)
- 규칙이므로 따라야 합니다 (formal obligation)
Negative Forms
Because Not
안 + Verb + -(으)므로:
- 안 좋으므로 (because it's not good)
- 안 되므로 (because it won't work)
Verb + -지 않으므로:
- 좋지 않으므로 (because it's not good)
- 되지 않으므로 (because it won't work)
Because There Isn't
없으므로:
- 시간이 없으므로 (because there's no time)
- 증거가 없으므로 (because there's no evidence)
Common Expressions
Official Notices
- 공사 중이므로 (because construction is ongoing)
- 휴업이므로 (because [we're] closed)
- 만원이므로 (because it's full)
- 위험하므로 (because it's dangerous)
Formal Reasons
- 중요하므로 (because it's important)
- 필요하므로 (because it's necessary)
- 규칙이므로 (because it's a rule)
- 사실이므로 (because it's a fact)
Legal/Academic
- 법으로 정해져 있으므로 (because it's established by law)
- 증명되었으므로 (because it's been proven)
- 연구 결과에 따르므로 (because according to research)
Comparison with Similar Patterns
-(으)므로 vs -아/어서
-(으)므로: Very formal, written
- 비가 오므로 우산이 필요합니다 (Because it's raining, an umbrella is needed)
- Formal documents, notices
-아/어서: Casual/neutral, spoken
- 비가 와서 우산이 필요해요 (Because it's raining, I need an umbrella)
- Daily conversation
-(으)므로 vs -기 때문에
-(으)므로: More formal
- 중요하므로 (because it's important - formal)
- Official contexts
-기 때문에: Less formal but still proper
- 중요하기 때문에 (because it's important - standard)
- Can be written or spoken
-(으)므로 vs -니까
-(으)므로: Formal, objective reason
- 사실이므로 믿으십시오 (Because it's a fact, please believe)
- Official statements
-니까: Casual, subjective
- 사실이니까 믿어 (Because it's a fact, believe me)
- Personal conversation
Common Mistakes
❌ Incorrect: 좋므로
Missing -으 with final consonant
✅ Correct: 좋으므로
Use -으므로 with final consonant
❌ Incorrect: 하으므로
Adding -으 without final consonant
✅ Correct: 하므로
Use -므로 with vowel ending
❌ Incorrect: Using in casual speech
"비가 오므로 갈 수 없어"
✅ Correct: Use appropriate pattern
"비가 와서 갈 수 없어" (casual)
Summary Table
| Type | Form | Example | Meaning |
|---|---|---|---|
| Vowel ending | -므로 | 가므로 | Because [one] goes |
| Consonant ending | -으므로 | 먹으므로 | Because [one] eats |
| Adjective (vowel) | -므로 | 크므로 | Because it's big |
| Adjective (cons.) | -으므로 | 좋으므로 | Because it's good |
| With 이다 (cons.) | 이므로 | 학생이므로 | Because [one is] a student |
| Negative | -지 않으므로 | 좋지 않으므로 | Because it's not good |
Usage Context Guide
Use -(으)므로 in:
✅ Official notices and signs ✅ Formal documents ✅ Academic writing ✅ News reports ✅ Legal texts ✅ Formal speeches ✅ Business correspondence
Don't use -(으)므로 in:
❌ Casual conversation ❌ Informal writing ❌ Text messages ❌ Daily speech ❌ Talking to friends/family
Alternative Patterns by Context
Casual Conversation
Use: -아/어서 or -니까
- 비가 와서 못 가요
- 비가 오니까 못 가요
Standard Polite
Use: -기 때문에
- 비가 오기 때문에 못 가요
Formal Written/Spoken
Use: -(으)므로
- 비가 오므로 갈 수 없습니다
Key Takeaways
- ✅ Very formal: Primarily written/official contexts
- ✅ Vowel harmony: -므로 vs -으므로
- ✅ Objective tone: Stating facts and reasons formally
- ✅ Not for casual use: Would sound strange in conversation
- ✅ Common in signs: Official notices and announcements
- ✅ Academic/legal: Standard in formal documents
-(으)므로 is essential for formal Korean writing and official contexts, but should be avoided in casual conversation where -아/어서, -니까, or -기 때문에 are more appropriate.