-히

하 (-ha-) +‎ 이 (-i, adverb-deriving suffix).

• (SK Standard/Seoul) IPA^(key): [çi]
• Phonetic hangul: [히]

히 • (-hi)

1. -ly; an adverb-deriving suffix, attaching primarily to adjectives formed by the light verb 하다 (hada).

   ‎솔직하다 (soljikhada, “to be honest”) + ‎히 (-hi) → ‎솔직히 (soljikhi, “honestly”)

   ‎깔끔하다 (kkalkkeumhada, “to be neat”) + ‎히 (-hi) → ‎깔끔히 (kkalkkeumhi, “neatly”)

This suffix coexists with 이 (-i), which is used for other adjectives. Generally speaking, 히 (-hi) is used for adjectives formed by 하다 (hada), and 이 (-i) is used for all other adjectives.

However, some 하다 adjectives lose the consonant ㅎ (-h-) entirely, taking 이 (-i) instead. In the prescriptive standard of Seoul Korean, there are two main exceptions:

• If the non-하다 element ends in ㅅ (-s), 이 is always used.

  ‎깨끗하 (kkaekkeutha-, “to be clean”) + ‎이 (-i) + ‎히 (-hi) → ‎깨끗이 (kkaekkeusi, “cleanly”)

• If the non-하다 element ends in ㄱ (-k), 이 is often used.

  ‎굵직하 (gukjikha-, “to be stout”) + ‎이 (-i) + ‎히 (-hi) → ‎굵직이 (gukjigi, “stoutly”)

In practice, many Seoul speakers will uniformly use 히 for all adverbs where the corresponding 하다 adjective remains current in the language.

For a few adverbs, the 히 form is prescriptively used despite being derived from non-하다 adjectives. However, most of these words have fallen out of use in spoken Korean. Note also that certain adverbs which originate as contractions of longer adverbs may use 히 even when there is no corresponding 하다 adjective for the contraction, and that some Sino-Korean adverbs with 히 have lost their adjectival counterpart entirely.