르-irregularity

In Korean morphology, a 르-irregular verb (ko: 르 불규칙 동사) is a type of irregular verb whose stem ends in 르.

Inflection

The 르-irregularity rules only apply when appending the infinitive -어 or any of its derivatives.e.g. -었어 or -어서. Under these circumstances, the following rules are applied:

• Add an additional ㄹ to the syllable preceding the final 르.

• Change the final 르 to ㄹ.

• Now add the infinitive-derived suffix.It is imperative that the suffix is appended after considering the 르-irregularity rules. This is not how all irregularity classes work! Take, for example, ㅂ-irregularity, which requires the suffix is added before considering the irregularity rules.

Examples

모르다

to not know

몰라요.

I know.

몰라서

because I do not know

몰랐어요.

I didn't know.

The -아 variant of the infinitive is used since the final vowel is ㅗ (not ㅡ, since we got rid of it!)