English joins two ideas with a little bridge-word sitting between two finished sentences — "I eat and I sleep," "it's raining but I'll go." Korean does something structurally different: it fuses the link straight into the first verb's ending and leaves that verb unfinished. The word that carries "and / but / because / if" is not a separate conjunction — it is a 연결어미 (connective ending) glued to the verb stem. Only the last verb in the sentence takes tense and the speech level. This page is the master index, grouping the major connectives by the meaning they express, so you can find the right ending by asking "what relationship do I want?" rather than memorizing them in a random list.
The master grid
The connectives here are level-invariant — they attach mid-clause, before politeness has arrived, so each has a single shape. Notation: -(으) = buffer 으 only after a consonant stem; 아/어 = harmony vowel (ㅏ/ㅗ → 아, else → 어, 하다 → 해).
| Function | Ending(s) | Example | Note |
|---|---|---|---|
| 나열 · 동시 — "and" | -고 -(으)며 (written) | 밥 먹고 자요 bap meokgo jayo | plain listing; no result carried over |
| 순차 — "and then" | -아/어서 -고 나서 | 가서 사요 gaseo sayo | -아서 carries the first act's result into the second |
| 대조 — "but" | -지만 -는데/은데 | 비싸지만 좋아요 bissajiman joayo | -는데 is the softer, more conversational contrast |
| 이유 — "because" | -아/어서 -(으)니까 -기 때문에 | 아파서 못 가요 apaseo mot gayo | -(으)니까 for commands/reasoning; -아서 for neutral cause |
| 조건 — "if / when" | -(으)면 -아야/어야 ("only if") | 시간이 있으면 sigani isseumyeon | -아야 = necessary condition ("only if / must") |
| 목적 — "in order to" | -(으)러 (+ 가다/오다) -(으)려고 -도록 | 먹으러 가요 meogeureo gayo | -(으)러 only with motion verbs; -(으)려고 = intention |
| 양보 — "even if" | -아/어도 -더라도 | 비싸도 사요 bissado sayo | -더라도 is the stronger, more hypothetical "even if" |
| 배경 — "setting-up" | -는데/은데 | 밥 먹는데 전화가 왔어요 bap meongneunde jeonhwaga wasseoyo | sets a stage for what follows |
"And" and "and then": -고 vs -아/어서
-고 simply lists two events with no claim that one flows from the other. -아/어서 in its sequential sense links them tightly: the first action's result is carried into the second — you go to a place and then do something there. 도서관에 가서 공부했어요 means you studied at the library you went to; 도서관에 가고 공부했어요 sounds like two unrelated acts.
저는 아침에 커피를 마시고 신문을 읽어요.
jeoneun achime keopireul masigo sinmuneul ilgeoyo
In the morning I drink coffee and read the paper. (-고, plain listing)
마트에 가서 우유랑 계란을 샀어요.
mateue gaseo uyurang gyeraneul sasseoyo
I went to the store and bought milk and eggs. (-아서, result carried over)
숙제를 다 하고 나서 게임했어요.
sukjereul da hago naseo geimhaesseoyo
After finishing all my homework, I played a game. (-고 나서, explicit 'after')
"But", "if", "in order to", "even if", "setting-up"
Each function has its go-to ending. Note the constraints in the grid: -(으)러 only rides on motion verbs (가다/오다), and -아야/어야 narrows "if" to "only if / must."
이 노트북은 좀 비싸지만 성능이 정말 좋아요.
i noteubugeun jom bissajiman seongneung-i jeongmal joayo
This laptop is a bit pricey, but the performance is really good. (-지만)
시간이 있으면 같이 영화 봐요.
sigani isseumyeon gachi yeonghwa bwayo
If you have time, let's watch a movie together. (-으면)
점심 먹으러 잠깐 나왔어요.
jeomsim meogeureo jamkkan nawasseoyo
I stepped out for a bit to have lunch. (-으러 + 나오다)
아무리 바빠도 아침은 꼭 챙겨 먹어요.
amuri bappado achimeun kkok chaenggyeo meogeoyo
No matter how busy I am, I always make sure to eat breakfast. (-아도)
밥 먹는데 갑자기 전화가 왔어요.
bap meongneunde gapjagi jeonhwaga wasseoyo
I was in the middle of eating when the phone suddenly rang. (-는데, background)
The one hard wall: -아/어서 and commands
Here is the constraint that separates natural Korean from textbook Korean. -아/어서 cannot take past tense on its own clause, and it cannot head a main clause that is an imperative or a propositive. Its two clauses fuse into one tightly-bound event chain, and a command is a fresh speech act, not a "consequence" that flows out of a fact. When your "because" is followed by a command, request, or suggestion, you must switch to -(으)니까.
길이 막히니까 지하철로 갑시다.
giri makinikka jihacheollo gapsida
The roads are jammed, so let's take the subway. (-(으)니까 → propositive is fine)
아프니까 오늘은 좀 쉬세요.
apeunikka oneureun jom swiseyo
You're not well, so please rest today. (-(으)니까 → command)
For tense, the same principle: the -아서 clause stays tenseless and the final verb carries the past — 어제 비가 와서 집에 있었어요, never ×왔아서.
Common Mistakes
1. Using -아서 before a command or suggestion. Only -(으)니까 can head an imperative main clause.
❌ 아파서 오늘은 쉬세요.
Wrong — -아서 can't head a command; use -(으)니까: 아프니까 쉬세요.
✅ 아프니까 오늘은 쉬세요.
apeunikka oneureun swiseyo
You're sick, so rest today.
2. Putting past tense on the -아서 clause. Tense lives only on the final verb.
❌ 어제 비가 왔아서 집에 있었어요.
Wrong — the -아서 clause is tenseless; the past goes on the final verb: 비가 와서 집에 있었어요.
✅ 어제 비가 와서 집에 있었어요.
eoje biga waseo jibe isseosseoyo
It rained yesterday, so I stayed home.
3. Using -고 where the two acts are location-linked and need -아서. 가고 breaks the "go there and do it" link.
❌ 친구를 만나고 커피를 마셨어요.
Reads as two unlinked acts. For 'meet a friend and (then, together) have coffee,' use 만나서: 친구를 만나서 커피를 마셨어요.
✅ 친구를 만나서 커피를 마셨어요.
chingureul mannaseo keopireul masyeosseoyo
I met a friend and we had coffee.
4. Dropping the 으 buffer after a consonant stem. -(으)러 and -(으)면 need it.
❌ 점심 먹러 갈래요?
Wrong — 먹- has a batchim, so the buffer is required: 먹으러.
✅ 점심 먹으러 갈래요?
jeomsim meogeureo gallaeyo?
Shall we go grab lunch?
Key Takeaways
- Korean joins clauses with connective endings on the first verb (SOV), not with conjunction words; only the final verb carries tense and politeness.
- Match ending to function: -고 (and), -아서 (and-then / because), -지만·-는데 (but), -(으)니까·-기 때문에 (because), -(으)면 (if), -(으)러·-(으)려고 (in order to), -아도·-더라도 (even if).
- -고 lists; -아/어서 carries the first act's result into the second (go there and do it).
- -아/어서 can't take its own past tense and can't head a command or "let's" — switch to -(으)니까 for those.
- After a consonant stem, keep the 으 buffer in -(으)면 / -(으)러 / -(으)니까.
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Start learning Korean→Related Topics
- Connective Endings 연결어미: How Korean Joins ClausesTOPIK 1 — Korean doesn't join clauses with separate words like 'and / but / because' — it fuses the link into the first verb's ending and leaves that verb unfinished, so only the final clause carries tense and the speech level.
- -아서 vs -(으)니까: Choosing Your 'Because'TOPIK 2 — The decisive side-by-side: -아서 states an objective cause and blocks commands, while -(으)니까 gives your own reasoning and freely heads an order or suggestion.
- Sentence-Final Endings by Speech Level (종결어미): Master GridTOPIK 3 — The full grid crossing Korean's four speech levels (합니다체 · 해요체 · 반말 · 한다체) with the four sentence types (statement · question · command · suggestion) — because the verb ending, not the word order or a helping word, carries both politeness and sentence type at once.
- Modifier (Attributive) Endings (관형사형 어미): Reference GridTOPIK 3 — The endings that turn a whole clause into a modifier sitting in front of a noun — Korean's relative clauses — crossed by predicate type and tense, with the crucial split: -는 marks a present-tense VERB, while -(으)ㄴ marks a present ADJECTIVE or a PAST verb.
- The Three Constraints: Tense, Subject & MoodTOPIK 2 — Connective endings aren't interchangeable synonyms of 'and / but / because' — each is a contract about three things: whether it can carry tense, whether the two clauses must share a subject, and whether a command or suggestion may follow.