Vowel Harmony – Korean Grammar Jargons #1

Vowel Harmony

-Vowel version of "Birds of a feather flock together" –

When you learn conjugation in Korean, you can see many pairs of grammar phrases that have same meaning. The examples are 아요/어요, 아서/어서, 아요/어요, 아야/어야, etc.

Some of you might have wondered why Korean has this complicated rule. It's because of Vowel Harmony, 모음 조화 in Korean. You might have guessed that this rule is only for Korean. However, according to Wikipedia, it happens in many other languages like Hungarian, Finnish, Estonian, Mongolian, etc.

In Wikipedia, vowel harmony is defined as long distance assimilatory process of vowels. It sounds a bit daunting. In short, it is a vowel version of "birds of a feather flock together."

In Korean, there are 3 types of vowels: Positive, Negative, Neutral. They are 양성모음, 음성모음, 중성모음 each in Korean. ㅏ, ㅗ and its variants like ㅑ, ㅛ, ㅘ, ㅚ, ㅐ are positive vowels. ㅓ, ㅜ and its variants like ㅕ, ㅠ, ㅟ, ㅝ, ㅔ are negative vowels. Positive vowel words like 막다 자다 오다 놀다 get along well with positive versions of grammar phrases like 아요, 아서, 았, 아야, etc. Negative vowel words like 숨다 먹다 울다 get along well with negative versions of grammar phrases like 어요, 어서, 었, 어야, etc.

Let's see some example sentences.

우리 회전 목마 타고 놀아요.
Let's ride carousel and have fun!

그만 울어요. 나까지 슬퍼지잖아.
Stop crying. You make me sad.

This rule was kept well until the Middle Age. However, this rule is broken after the vowel 아래 아(ㆍ) disappeared in Korean. 아래 아 and ㅡ were the pair and the pair is now broken.

Exception 1. ㅐ, ㅚ

I told you that ㅐ and ㅚ are positive vowels. However, they work with negative version of grammar phrases when they conjugate.

Let's see some examples.

침 좀 그만 뱉어. 지저분해!
Stop spitting. It's too dirty!

그 아이는 선생님이 되었어.
That boy became a teacher.

뱉다 meaning spit, speak out some word has positive vowel but it works with 어.
되다 meaning to become has positive vowel, ㅚ, but it works with 었.

Because of this change, this vowel harmony rule can be practically defined like this:

ㅏ, ㅗ work with positive versions of grammar phrases.
Other vowels except those two work with negative versions of grammar phrases.

Exception 2. Onomatopoeia, Mimetic Words

This rule is also broken in many onomatopoeia and mimetic words like 깡충깡충, 오순도순. Although those words are standard, there are many people who prefer to use 깡총깡총 and 오손도손.

Exception 3. ㅂ irregular

Most ㅏ, ㅗ verbs use positive grammar phrases, but there are still exceptions. ㅂ irregular verbs like 자연스럽다(natural), 놀랍다(amazing), 아름답다(beautiful), 더럽다(dirty), 새롭다(new), 날카롭다(sharp, pointed) use negative vowel phrases like, 워요, 워야, 워서, etc.

The verb 자연스럽다 is conjugated like 자연스러워요, 자연스러워야, 자연스러워서.
The verb 아름답다 is conjugated like 아름다워요, 아름다워야, 아름다워서.

돕다, 곱다: Words that Follow the Rule

It might be happy for you and me if the rule ends here, but there are still exceptions in two ㅂ irregular verbs, 돕다(help) and 곱다(pretty).

돕다 is conjugated like 도와요, 도와야, 도와서.
곱다 is conjugated like 고와요, 고와야, 고와서, etc.

As it is a bit confusing, some people use 와 with other ㅂ irregular verbs. Korean version of Amazing Grace, 나같은 죄인 살리신. The first half is like this, 나같은 죄인 살리신, 그 은혜 놀라워.

In some old 찬송가s(Psalm book), it is written like 놀라와. However, 놀라워 is correct. I don't know whether the makers of 찬송가 did it on purpose, but if they did, they might have tried to make it rhythmical. But it is grammatically wrong.


Amazing Grace was No. 405. However, it is changed to 305 after the revision of 찬송가.


  • ㅏ, ㅗ -> 아서, 았, 아야,
  • Other -> 어서, 었, 어야
  • ㅂ irregular -> 워서, 워야, 워요
  • 돕다, 곱다 -> 와서, 와야, 와요.