고 (go) · 서 (seo)
'고' connects actions or states in sequence or enumeration, while '서' expresses cause or reason between clauses.
One lane per word — no nested boxes, just the gist.
A connective ending used to simply list or connect two actions or states sequentially
When to use
Listing actions, Simultaneous actions, Connecting states
The nuance
Used when the clauses are connected in temporal sequence or enumeration without causal relationship.
A connective ending used when the first clause is the cause or reason for the second clause
When to use
Cause/reason, Result connection, Motivation for action
The nuance
Used when the first clause provides the cause or reason for the second clause.
나는 밥을 먹고 학교에 갔어요.
na-neun bap-eul meok-go hak-gyo-e gass-eo-yo., na neun bap eul meok go hak gyo e gass eo yo.
Two actions are naturally connected in temporal order.
나는 밥을 먹어서 학교에 갔어요.
na-neun bap-eul meok-eo-seo hak-gyo-e gass-eo-yo., na neun bap eul meok eo seo hak gyo e gass eo yo.
'Eating rice' is not a cause for 'going to school,' so the cause relationship does not hold.
비가 와서 길이 미끄러워요.
bi-ga wa-seo gil-i mi-kkeu-reo-wo-yo., bi ga wa seo gil i mi kkeu reo wo yo.
Rain is the cause of slippery roads, so '서' is appropriate.
비가 오고 길이 미끄러워요.
bi-ga o-go gil-i mi-kkeu-reo-wo-yo., bi ga o go gil i mi kkeu reo wo yo.
Simply listing two states, so '고' is correct.
친구를 만나고 영화를 봤어요.
chin-gu-reul man-na-go yeong-hwa-reul bwass-eo-yo., chin gu reul man na go yeong hwa reul bwass eo yo.
Two actions connected sequentially, natural usage.
친구를 만나서 영화를 봤어요.
chin-gu-reul man-na-seo yeong-hwa-reul bwass-eo-yo., chin gu reul man na seo yeong hwa reul bwass eo yo.
Meeting a friend can be the motivation or reason for watching a movie.
피곤해서 일찍 잤어요.
pi-gon-hae-seo il-jjik jass-eo-yo., pi gon hae seo il jjik jass eo yo.
Being tired is the cause for sleeping early, so '서' is appropriate.
피곤하고 일찍 잤어요.
pi-gon-ha-go il-jjik jass-eo-yo., pi gon ha go il jjik jass eo yo.
Though it looks like listing, it is inappropriate when expressing cause and effect.
Which sentence shows a cause and effect relationship?
Which sentence expresses a list of actions?
What is the role of '서' in "친구를 만나서 영화를 봤어요."?
