Grammar
N끼리
Meaning
BeginnerN kkiri
Attaches to a noun that stands for more than one, and says that whatever happens, happens among those members and nobody outside: 학생들끼리 이야기를 나눴습니다 is students talking to each other with no one else in the conversation. Because the noun in front has to be a group, the word carries a built-in claim of sameness — 친구끼리 is among friends, never with a friend. Korean uses it both for who takes part (우리끼리, 부모끼리, 나라끼리) and for what gets sorted with what (같은 색끼리 모으다).
Form
끼리 attaches straight to a noun with no space and no change for a final consonant (학생들끼리, 우리끼리, 나라끼리). What comes in front has to name more than one — a noun marked with 들, a plural pronoun, or a noun that already stands for a class (팀끼리, 회원끼리) — so it does not attach to a single named individual. It stands in place of 이/가, 은/는 and 을/를, which is why 학생들끼리 이야기했다 needs no further subject marker, and it takes 의 when the phrase modifies a following noun (선수들끼리의 경기). It attaches to nouns only, never to a verb ending.
Examples
학생들끼리 이야기를 나눴습니다.
The students talked among themselves.
Common mistakes & nuance
끼리 does two jobs at once and the second is easy to miss. It says the participants are all of one kind, and it says the action does not reach outside them — which is why 지역 대표팀끼리 경기를 합니다 rules out a match against anyone else, and why 우리끼리 이야기 reads as a conversation others are not part of. That exclusive edge means it is not a neutral 'with': 친구와 갔다 is went with a friend, while 친구끼리 갔다 is a group of friends went and nobody else came along. In everyday speech that can sound cliquish, so a speaker choosing 끼리 over 함께 is usually making a point rather than just describing company. Note too that 끼리 never counts — it says the members are alike, not how many there are — and that 들끼리 is normal rather than redundant, since the 들 is what makes the noun plural in the first place.
Similar grammar
- 마다
Both attach to a group noun, and then split it in opposite directions. 마다 takes the group apart and applies the statement to each member on its own (사람마다 다르다 — it differs from person to person, each one considered separately). 끼리 holds the group together and keeps the action inside it (사람들끼리 다르다 would not mean that). The quick test: if the members are being counted off one by one, it is 마다; if they are doing something to or with each other, it is 끼리.
- N만
Both shut outsiders out, but they cut in different places. 만 limits who or what the statement is about (학생들만 참가했습니다 — the participants were students and nobody else was). 끼리 limits how far the action reaches, leaving the membership question alone (학생들끼리 참가했습니다 — the students took part as a self-contained group). A sentence can want both at once, and Korean simply stacks them: 우리끼리만.