Posted: 2010-06-22 / Updated: 2018-02-07

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

We know a regular verb in English may be modified to its past tense form by adding suffix ed to it, and English adjectives use verb to be (e.g. was) to represent past tense.

In Korean, however, adjectives are verb-like in grammatical constructions, and both verbs and adjectives follow a similar set of rules to Essential Concepts and Terms for Grammar Study to their modified forms.

Korean verbs and adjectives are mostly regular, meaning that they follow a simple rule to conjugate. For the remaining irregular verbs and adjectives, the good news is, they are not as “irregular” as English verbs. There is one set of conjugation rules for each group of irregular verbs and adjectives.

Word stem is the basic unit to conjugate. Regular verb or adjective only has an original stem for conjugation. Irregular verb or adjective has an additional alternate stem, as explained in the section below.

Original Stems of Korean Verbs and Adjectives

When a Korean verb or adjective is in plain form (the form you can look up from a dictionary), it always ends with .

It is then easy to identify the original stem:

Get the original stem of any verb or adjective by removing the last hangul 다 of the plain form of the word.

Alternate Stems of Korean Verbs and Adjectives

You will need to know what kind of irregular verb/adjective it is, before identifying its alternate stem.

Verbs/AdjectivesAlternate Stem Formation from Original Stem
RegularKeep the original stem unchanged
ㅂ-IrregularDrop final consonant ㅂ, add hangul 우**
ㅅ-IrregularDrop final consonant ㅅ
ㄷ-IrregularReplace final consonant ㄷ with ㄹ
ㅎ-IrregularDrop final consonant ㅎ
ㄹ-IrregularDrop final consonant ㄹ
으-IrregularKeep the original stem unchanged
르-IrregularAdd ㄹ as an ending consonant to the second to last hangul

** There is an additional alternate stem for 2 ㅂ-irregular words for Korean Verb and Adjective Conjugation: 돕다 (to help) and 곱다 (to be pretty), by replacing the final consonant ㅂ with hangul 오.


Verbs/AdjectivesDictionary FormMeaningOriginal StemAlternate Stem
돕다help도우 or 도오
ㅎ-Irregular그렇다to be so그렇그러

See Formal Polite Form of Korean Verbs and Adjectives for examples of using original stems for conjugation. See Informal Polite Form of Korean Verbs and Adjectives for examples of using alternate stems for conjugation.

There is no definitive rule to identify if a verb/adjective is regular or not. However, by looking at the final consonant of the original stem, you can tell it is not irregular if it does not have the irregular stem ending.

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