Morphological Passive -이-

The first of the four fused passive suffixes is -이-. It slots between a transitive stem and its ending, turning "do X" into "be X-ed": 보다 ("see") becomes 보이다 ("be seen, be visible"), 놓다 ("put") becomes 놓이다 ("be placed"). Like all the suffix passives, the set is closed and memorized — you learn which verbs take -이- rather than deriving it. But -이- rewards a close look, because it teaches two things the other suffixes also do: how a Korean passive often lands as an English state adjective rather than a be-passive, and how the suffix pairs with -아/어 있다 to describe a lingering result. It also hides a famous trap — 보이다 is a passive and a causative at the same time.

The -이- verbs

Here is the core memorized set. These stems happen to end in a vowel or in ㅎ, ㄲ, or ㅍ (plain ㄱ and ㅂ stems generally take 히 instead — 먹히다, 잡히다), but the assignment is lexical, not predictable, so treat each as vocabulary.

The passive that lands as a state adjective

Here is the insight 보이다 hands you. English keeps the be-passive ("is seen") separate from the state adjective ("is visible"), but Korean's -이- passive often maps onto the adjective side. 보이다 rarely means "is being seen by someone"; it means "is visible" — a property of the scene, no viewer implied. The same is true of 들리다 ("be heard" → "is audible") from the 히/리 passives.

So when you translate an English "can see / can hear / is visible / is audible," reach for 보이다 / 들리다, not a "can" construction. 산이 보여요 is the natural Korean for "I can see the mountain" — the mountain simply is visible, and the seer is left unstated.

Pairing with -아/어 있다: the lingering result

The suffix passive frequently combines with -아/어 있다 to say that a thing is in the resulting state of the action — placed, piled, covered, and staying that way. 놓이다 ("be placed") plus 있다 gives 놓여 있다 ("is [sitting there] placed"). This is the standard way to describe how things are arranged in a space.

The difference from a plain past tense is aspect: 눈이 쌓였어요 reports the event ("snow piled up"), while 눈이 쌓여 있어요 describes the ongoing state ("snow is [now] in a piled-up condition"). For that distinction across verbs, see the resultative -아/어 있다 and its neighbours.

The famous trap: 보이다 is also a causative

This is the wrinkle that makes -이- worth studying. The suffix -이- builds both passives and causatives, and for a few verbs the same fused form does both jobs. 보이다 is the star example: it is the passive of 보다 ("be seen / be visible") and the causative of 보다 ("to show" = make someone see). Same four letters, opposite voice.

What tells them apart is the particles, not the verb. In the passive, the thing seen is the subject (바다가 보여요 — the sea is visible). In the causative, the thing shown is the object (여권을 보여 주세요 — show the passport), and there is an implied shower and a person shown to. Same logic runs through other -이- verbs that double as causatives; the full disambiguation lives on the passive–causative homophone page. Which stems take -이- as opposed to 히/리/기 is mapped on choosing the passive suffix.

Common Mistakes

1. Doubling the suffix with -어지다 (×보여지다). The single most common -이- error. 보이다 is already passive; adding 지다 double-marks it. You will hear 보여지다 and 놓여지다 constantly in real life, but they are prescriptively wrong (이중피동, "double passive") — use the bare suffix form.

2. ×놓여져 있다 instead of 놓여 있다. Same doubling, this time inside the resultative.

3. Confusing the passive with the plain verb's object. 보다 takes an object (영화를 봐요 "watch a movie"); 보이다 takes a subject (별이 보여요 "the stars are visible"). Marking the visible thing as an object is an error.

4. Using a plain past where the -아/어 있다 state is meant. To describe how things currently sit, use the resultative, not a bare past.

Key Takeaways

• -이- fuses onto a fixed set of stems to make a passive: 보이다 (be visible), 놓이다 (be placed), 쌓이다 (accumulate), 섞이다 (be mixed), 덮이다 (be covered), 바뀌다 (be changed).
• It often reads as an English state adjective: 보이다 ≈ "is visible / can see," 들리다 ≈ "is audible / can hear."
• It pairs with -아/어 있다 for the lingering result (놓여 있다 "is placed," 쌓여 있다 "is piled up").
• 보이다 is a passive and a causative ("to show"); the particles (subject vs object) disambiguate.
• Never add -어지다 on top of it: ×보여지다, ×놓여지다 are double passives — use 보여요, 놓여 있어요.