원인 (won-in, wonin) · 이유 (i-yu, iyu) · 목적 (mok-jeok, mokjeok)
원인, 이유, 목적 all answer 'why', but 원인 refers to the fundamental cause of an event, 이유 explains personal or situational reasons, and 목적 expresses intention or goals.
One lane per word — no nested boxes, just the gist.
The fundamental cause or factor that made an event or condition happen
When to use
cause of accident, cause of disease, cause of natural phenomenon
The nuance
원인 is used mainly to explain objective, factual causes of events, unrelated to feelings or intentions.
The reason or motive that explains a person's action or situation
When to use
explaining motivation, reason for decision, reason for feelings
The nuance
이유 is used for subjective explanations involving people or situations, often including feelings or judgments.
The goal or intention that an action or plan aims to achieve
When to use
goal of plan, intention of action, project purpose
The nuance
목적 expresses intention and goals, generally future-oriented and planned.
사고의 원인을 조사하고 있다.
sa-go-ui won-in-eul jo-sa-ha-go iss-da., sa go ui won in eul jo sa ha go iss da.
Appropriate use of 원인 to explain the fundamental cause of an accident objectively.
그가 늦은 이유는 교통 체증 때문이다.
geu-ga neuj-eun i-yu-neun gyo-tong che-jeung ttae-mun-i-da., geu ga neuj eun i yu neun gyo tong che jeung ttae mun i da.
Correct use of 이유 to explain a person's reason for being late.
우리는 회의의 원목을 정해야 한다.
u-ri-neun hoe-ui-ui won-mok-eul jeong-hae-ya han-da., u ri neun hoe ui ui won mok eul jeong hae ya han da.
'원목' is incorrect; should use '목적' to mean purpose.
질병의 이유를 알 수 없다.
jil-byeong-ui i-yu-reul al su eop-da., jil byeong ui i yu reul al su eop da.
For objective causes of disease, '원인' should be used, not '이유'.
이 프로젝트의 목적은 시장 점유율 확대이다.
i peu-ro-jek-teu-ui mok-jeok-eun si-jang jeom-yu-yul hwak-dae-i-da., i peu ro jek teu ui mok jeok eun si jang jeom yu yul hwak dae i da.
Appropriate use of 목적 to express the goal of a project.
그가 화난 원인은 친구의 무례한 말 때문이다.
geu-ga hwa-nan won-in-eun chin-gu-ui mu-rye-han mal ttae-mun-i-da., geu ga hwa nan won in eun chin gu ui mu rye han mal ttae mun i da.
For explaining emotional reasons, '이유' is correct; '원인' is inappropriate.
그녀가 회사를 그만둔 원인은 개인적인 사정이다.
geu-nyeo-ga hoe-sa-reul geu-man-dun won-in-eun gae-in-jeok-in sa-jeong-i-da., geu nyeo ga hoe sa reul geu man dun won in eun gae in jeok in sa jeong i da.
Personal motives require '이유', not '원인'.
새로운 정책의 목적은 환경 보호이다.
sae-ro-un jeong-chaek-ui mok-jeok-eun hwan-gyeong bo-ho-i-da., sae ro un jeong chaek ui mok jeok eun hwan gyeong bo ho i da.
Correct use of 목적 to indicate the goal of a policy.
Which word is appropriate to describe the fundamental cause of an accident?
Which word fits when explaining a person's motivation for an action?
Which word is suitable to express a goal intended to be achieved in the future?
