Posted: 2010-06-23 / Updated: 2018-02-07

To study this grammar point, please make sure you understand the following:


Essential Concepts and Terms for Grammar Study is to modify of a verb or an adjective in order to fulfil a change in tense or to supplement additional meanings.

All Korean conjugation for verbs and adjectives are under one of the following 3 categories:

  1. 고-type: Original Stem + Suffix
  2. 으-type: Alternate Stem + (으) + Suffix
  3. 어-type: Alternate Stem + 어/아 + Suffix, Vowel Contractions

The basic idea is to Word Stems of Korean Verbs and Adjectives and attach a suffix to the stem.

1. 고-type Conjugation

This is named after the basic 하고 conjugation. Word Stems of Korean Verbs and Adjectives is always used, with the following exceptions:

  • For ㄹ-irregular, when the attaching suffix starts with , or (e.g. 는, 네, 습니다), alternate stem is used (i.e. ㄹ is dropped).
  • For ㅎ-irregular, use alternate stem when the attaching suffix is .
Plain FormMeaningStem 1Stem 2+고+습/ㅂ니다+네Remarks
하다do하고하습니다하네
먹다eat먹고먹습니다먹네
알다know알고압니다아네ㄹ-irregular
그렇다to be so그렇그러그렇고그렇습니다그러네ㅎ-irregular

Note: Original Stem = Stem 1, Alternate Stem = Stem 2.

2. 으-type Conjugation

Use Word Stems of Korean Verbs and Adjectives and if the stem ends with a consonant, insert after the stem.

However, there are 3 exceptions:

  1. For ㅅ-irregular, 으 is always inserted.
  2. For ㄹ-irregular, if the suffix starts with 면 or 러, use original stem and do not insert 으.
  3. For 르-irregular, use original stem instead.

Examples

Plain FormMeaningStem 1Stem 2+ (으)세요+ (으)면+ (으)러Remarks
하다do하세요하면하러
먹다eat먹으세요먹으면먹으러
알다know아세요알면알러ㄹ-irregular
짓다build지으세요지으면지으러ㅅ-irregular
고르다choose고르고르세요고르면고르러르-irregular

3. 어-type Conjugation

You can consider 어-type conjugation as a 2-step process. First you need to determine whether 아 or 어 should be attached, then you need to do a vowel contraction if necessary.

Use Word Stems of Korean Verbs and Adjectives as word stem for all 어-type conjugation, except that for ㄹ-irregular, use Word Stems of Korean Verbs and Adjectives instead.*

The following rules determine whether to attach 어 or 아 before the suffix:

  1. If the last vowel of the stem is a 오 or 아, attach 아 + suffix.
  2. If the last vowel is 으 and its previous hangul has a 오/아 vowel, attach 아 + suffix.
  3. Otherwise, attach 어 + suffix.

Next, if the stem has no ending consonant, contract the last vowel of the stem and the added 아/어 as shown in the table below. Pay special attention to 하다-related verbs and adjectives, and ㅅ-irregular, as they are the exceptions.*

CaseContractionExampleMeaningStem + 아/어요Remarks
*하 +아 → 해공부하다study공부하 + 아요 → 공부해요하다-related
1아 +아 → 아가다go가 +아요 → 가요
오 +아 → 와오다come오 +아요 → 와요
돕다help도오 +아요 → 도와요ㅂ-irregular
2으 +아 → 아바쁘다busy바쁘 +아요 → 바빠요으-irregular
고르다choose골르 +아요 → 골라요르-irregular
3우 +어 → 워배우다learn배우 +어요 → 배워요
춥다cold추우 +어요 → 추워요ㅂ-irregular
으 +어 → 어쓰다write쓰 +어요 → 써요으-irregular
부르다call불르 +어요 → 불러요르-irregular
이 +어 → 여치다hit치 +어요 → 쳐요
어 +어 → 어 or 애건너다go over건너 +어요 → 건너요
그렇다to be so그러 +어요 → 그래요ㅎ-irregular
외 +어 → 왜되다become되 +어요 → 돼요
애 +어 → 애지내다spend time지내 +어요 → 지내요
여 +어 → 여펴다unfold펴 +어요 → 펴요
AllNo Contraction먹다eat먹 +어요 → 먹어요
듣다listen들 +어요 → 들어요ㄷ-irregular
놀다play놀 +아요 → 놀아요ㄹ-irregular*
낫다get better나 +아요 → 나아요ㅅ-irregular*
Use original stem for ㄹ-irregular, and never do vowel contractions forㅅ-irregular.

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