-기-

From Middle Korean 기〮 (Yale: -kí-, causative/passive-deriving suffix). Beyond Middle Korean, the causative is the original meaning as attested in Old Korean, and the passive is a later development from the causative, first attested in the written language some time between the thirteenth and fifteenth centuries.[1][2]

기 • (-gi-)

1. A verbal suffix deriving the stems of causative verbs, particularly but not exclusively attaching to verb or adjective stems which end in ㅁ (m), ㄴ (n), or ㅅ (s). No longer productive.

   Synonyms: 이 (-i-), 히 (-hi-), 리 (-ri-), 우 (-u-), 구 (-gu-), 추 (-chu-)

   ‎신다 (sinda, “to wear (shoes)”) + ‎기 (-gi-) → ‎신기다 (sin'gida, “to make someone wear shoes”)

   ‎남다 (namda, “to remain”) + ‎기 (-gi-) → ‎남기다 (namgida, “to leave behind”)

   ‎웃다 (utda, “to laugh”) + ‎기 (-gi-) → ‎웃기다 (utgida, “to be funny”)

   ‎맡다 (matda, “to take charge of”) + ‎기 (-gi-) → ‎맡기다 (matgida, “to assign”)

2. A verbal suffix deriving the stems of passive verbs, particularly but not exclusively attaching to verb or adjective stems which end in ㅁ (m), ㄴ (n), or ㅅ (s). No longer productive.

   Synonyms: 이 (-i-), 히 (-hi-), 리 (-ri-)

   ‎안다 (anda, “to hug”) + ‎기 (-gi-) → ‎안기다 (an'gida, “to be hugged”)

   ‎믿다 (mitda, “to believe”) + ‎기 (-gi-) → ‎믿기다 (mitgida, “to be believable”)

   ‎빼앗다 (ppaeatda, “to rob, to take away from”) + ‎기 (-gi-) → ‎빼앗기다 (ppaeatgida, “to be dispossessed”)

Although still very common in Korean, the causative/passive suffixes are no longer productive for forming new verbs. Verbs that do not already have a morphological causative or passive must employ auxiliaries:

• 게 하다 (-ge hada) for causatives
• 어지다 (-eojida) for passives

The causative/passive suffixes 이 (-i-), 히 (-hi-), 리 (-ri-), and 기 (-gi-) all stem from the same etymon, and are fairly complementary in distribution. 기 tends to attaches to verb stems which end in a nasal or a sibilant, although there are several prominent exceptions.