Passive & Causative Voice (이/히/리/기)

Form the passive by inserting one of four infixes into the verb stem: -이- (보다→보이다, 쓰다→쓰이다), -히- (잡다→잡히다, 닫다→닫히다), -리- (열다→열리다, 듣다→들리다), -기- (안다→안기다, 쫓다→쫓기다). The original object becomes the subject (marked 이/가), and the original subject (the agent) is marked with 에게/한테 (people/animals) or 에 (things/forces). There is no single rule for which infix a verb takes — they must be memorized per verb.

Attach -아지다/-어지다 to a verb stem to express a passive or spontaneous change of state, especially when no clear agent is involved or the result 'just happens'. Use this for verbs that have no 이/히/리/기 form: 만들다→만들어지다 (be made), 켜다→켜지다 (turn on), 끊다→끊어지다 (be cut/disconnected). With adjectives the same ending means 'become' (예뻐지다 = become pretty), which is related but distinct from passive.

The same infixes 이/히/리/기 (plus 우/구/추) also form causatives, meaning 'make/let someone do': 먹다→먹이다 (feed), 입다→입히다 (dress), 살다→살리다 (save/revive), 웃다→웃기다 (make laugh), 자다→재우다 (put to sleep). The causee is marked with 에게/한테 (or 을/를 for direct manipulation). For Sino-Korean action nouns, add 시키다: 공부시키다 (make study), 진정시키다 (calm down). Note 먹이다 can be both passive 'be eaten by' context-dependent — context disambiguates.

The most productive and regular causative: attach -게 하다 ('make/let someone do') to ANY verb or adjective stem. Unlike the suffixal causative (which often implies direct hands-on action), -게 하다 covers both 'make' (coercion) and 'let' (permission), and is the safe choice when no special causative form exists. -게 만들다 stresses the result/'cause to become'. The causee takes 이/가 or 을/를; subtle nuance differences exist between them.

Sino-Korean action nouns become passive without infixes by switching the light verb. 하다 (do) → 되다 for neutral passive (해결하다→해결되다 be solved, 사용하다→사용되다 be used); → 받다 for benefactive/received passive (존경하다→존경받다 be respected, 사랑→사랑받다 be loved); → 당하다 for adversative passive of something bad (무시하다→무시당하다 be ignored/snubbed, 사기→사기당하다 be scammed). Choosing the wrong light verb changes the emotional coloring of the sentence.