Morphological Causative -히-

-히- is the causative suffix that steps in where -이- cannot go. When a verb stem ends in an obstruent — ㄱ, ㄷ, ㅂ, ㅈ, or the cluster ㄺ — the language reaches for 히 instead of 이, and the ㅎ of the suffix fuses with that final consonant into an aspirated sound: 입 + 히 → [이피], 익 + 히 → [이키]. That fusion is the audible signature of -히- causatives, and it is why they sound so different from their base verbs. This page covers the productive -히- set — seating, dressing, laying down, widening — plus two verbs, 익히다 and 읽히다, that carry a hidden second meaning.

How -히- builds a causative

Insert 히 between stem and ending, exactly like -이-: 앉 + 히 + 다 → 앉히다. The result is transitive: the base verb's subject becomes the new object.

Compare 아이가 앉아요 ("the child sits") with the causative 아이를 앉혀요 ("I sit the child") — the sitter becomes the one made to sit. The past is 앉혔어요 (ancheosseoyo), the present 앉혀요 (ancheoyo). The whole -히- family conjugates as regular 히다-stem verbs.

The -히- inventory and its aspiration

Here is the productive core. The bracketed form is the pronunciation, and it is the point of the page — watch the aspiration born from ㅎ-fusion:

The mechanism is uniform: stop + ㅎ → aspirated stop. ㅂ + ㅎ → ㅍ (입히다 [이피다], 눕히다 [누피다], 좁히다 [조피다]); ㄱ + ㅎ → ㅋ (익히다 [이키다], and in ㄺ the ㄹ stays while ㄱ aspirates: 읽히다 [일키다], 넓히다 keeps ㄹ and aspirates ㅂ → [널피다]); ㄵ contributes ㅈ + ㅎ → ㅊ (앉히다 [안치다]). This is the same aspiration Revised Romanization shows in 좋다 → jota — so the romanizations above carry the fused sound.

Note that 넓히다 and 좁히다 come from adjectives (넓다 "be wide," 좁다 "be narrow"), so the causative reads as "make wider / make narrower" — a change of the object's dimension.

익히다: cook it — or master it

익히다 earns its keep twice. Literally, from 익다 ("be cooked, ripen"), it means "cook something thoroughly, cook through":

But 익히다 has a second, fully lexicalized life meaning "to master, get the hang of, make (a skill) your own" — you "cook" a skill until it's done, until it's yours. This idiom is extremely common with 기술 (skill), 실력, 습관, and languages.

Both senses share one form and one pronunciation, [이키다]; the object (meat vs. a skill) tells you which. Treat the "master" sense as its own vocabulary item, not as something you'd predict from "cook."

읽히다: another causative/passive homophone

읽히다 ([일키다]) is, like 보이다, ambiguous between causative ("make/let read") and passive ("be read, read easily") — resolved by context and particles.

The causative marks the reader with 에게 and the text with 을/를; the passive puts the text itself in subject position (이 소설은 … 읽혀요) with no reader named. The full set of these overlaps lives on the passive/causative homophone page; the passive -히- page handles 읽히다's passive twin directly.

Why 히 and not 이 here

The choice is partly phonological and partly lexical. After ㄷ/ㅈ/ㄺ and often ㅂ, inserting bare 이 would produce awkward clusters, so 히 — whose ㅎ readily fuses — is preferred. But do not over-trust the consonant: it is a tendency, not a law. The ㄱ-final 익다 takes 히 (익히다), yet the ㄱ-final 먹다 takes 이 (먹이다); the ㄹ-final 줄다 takes 이 (줄이다), not 리. In the end, the suffix is memorized per verb, and the surrounding consonant only nudges the odds. The suffix-selection page maps the whole terrain; here, bank the -히- set as a list. Its sister pages are -이- and -리-.

Common Mistakes

1. Defaulting to -이- for a ㅂ-final stem. "Dress someone" is 입히다, not ×입이다.

2. Same error with 앉다. "Seat someone" is 앉히다.

3. Losing the aspiration in speech. 입히다 is [이피다], not ×[이비다]; the ㅂ must aspirate to ㅍ.

4. Missing 익히다's "master" sense. With 기술 / 일 / 언어, 익히다 means "get the hang of," not "cook."

5. Reading 읽히다 only as causative. In subject position with no reader named, it's the passive "be read / read easily."

Key Takeaways

• -히- is the causative suffix for ㄱ / ㄷ / ㅂ / ㅈ / ㄺ-final stems where 이 won't fit: 앉히다, 입히다, 눕히다, 넓히다, 좁히다.
• Its signature is aspiration from ㅎ-fusion: ㅂ+ㅎ → ㅍ, ㄱ+ㅎ → ㅋ, ㅈ+ㅎ → ㅊ — hence 입히다 [이피다], 익히다 [이키다], 앉히다 [안치다].
• 익히다 = "cook thoroughly" and the idiom "master / get the hang of."
• 읽히다 is a causative/passive homophone — "make read" vs. "be read."
• Consonant shape only hints; the actual suffix is memorized per verb (익다 → 히 but 먹다 → 이).