Irregular 르 Verbs

This grammar kicks in when a verb stem ending in 르 meets a suffix starting with a vowel. Specifically, this happens with the 아/어 endings. These are used for the polite present tense, past tense, and many connecting forms. When this happens, the ㅡ vowel in 르 disappears completely. In its place, an extra ㄹ is born. This new ㄹ attaches itself to the bottom of the previous syllable. Then, another ㄹ stays with the ending. It is like the original ㄹ split into two. One goes back to the previous block, and one stays forward. This creates a double ㄹ sound that is very characteristic of Korean. If the ending doesn't start with 아 or 어, the verb stays totally regular. It is like a secret identity that only comes out when vowels are around. Think of it like a grammar traffic light. The vowel is the green light that tells the ㄹ to double up.

1. 1Identify the verb stem ending in 르. For example, 모르다 (to not know).
2. 2Check the syllable right before 르. Look at its vowel.
3. 3If that vowel is ㅏ or ㅗ, you will use 아 based endings. If it is anything else, use 어 based endings.
4. 4Drop the ㅡ from 르 completely.
5. 5Add an extra ㄹ to the bottom (patchim) of the syllable before 르.
6. 6Change the remaining ㄹ into 라 (if the previous vowel was ㅏ/ㅗ) or 러 (for everything else).
7. 7Let's look at 모르다. The syllable before 르 is 모. The vowel is ㅗ. So we add ㄹ to 모 to get 몰. Then we add 라요. The result is 몰라요. Now let's try 부르다 (to call/sing). The syllable before is 부. The vowel is ㅜ. This is not ㅏ or ㅗ. So we add ㄹ to 부 to get 불. Then we add 러요. The result is 불러요. It is a simple two-step dance: double the ㄹ, then pick the right vowel.

Use this pattern whenever you are using the present or past tense with 르 verbs. You will use it when ordering food quickly using 빠르다 (to be fast). It is essential when you want to say your opinion is different using 다르다. If you are singing a song, you'll use 부르다. It is also used in common phrases like "I don't know" (몰라요). You will use it when choosing items while shopping with 고르다. Even when describing the weather or nature, like a river flowing (흐르다), this rule applies. It is a workhorse of the Korean language. Whether you are in a job interview or chatting with a friend, these verbs will show up. They are unavoidable, so it is best to make friends with them now.

This rule only applies when the next part of the word starts with 아 or 어. If the suffix starts with a consonant, the verb stays regular. For example, if you use -고 (and), 모르다 just becomes 모르고. No doubling happens here. If you use -니 or -면, it stays 모르니 and 모르면. The ㄹ is shy and only doubles up when it sees a vowel. Also, be careful with the formal -습니다 ending. Since it starts with a consonant, 모르다 becomes 모릅니다. There is no ㄹ doubling in the formal style. Finally, a tiny handful of verbs look like 르 verbs but are actually regular ㅡ irregulars. The most famous one is 따르다 (to follow). It becomes 따라요, not 딸라요. Yes, even native speakers mess this up sometimes, so don't sweat it too much.

The biggest mistake is forgetting the extra ㄹ. Many people say 모라요 instead of 몰라요. This sounds very unnatural to Korean ears. It's like saying "I don't no" instead of "I don't know." Another mistake is picking the wrong vowel. Some say 몰러요 because they forgot to check the ㅗ in 모. Always look at the syllable before the 르. Another common error is applying the rule when it isn't needed. Don't say 몰고 for 모르고. Consonants don't trigger the change. Lastly, don't confuse 르 irregulars with regular verbs that happen to end in ㄹ. They are different families. Think of the extra ㄹ as a mandatory teammate. If you leave him on the bench, your sentence won't win.

You might confuse this with the ㅡ irregular rule (like 쓰다 -> 써요). In the ㅡ rule, the vowel just drops. There is no extra ㄹ added. But in the 르 rule, we always add that extra ㄹ. Also, contrast this with ㄹ irregulars (like 살다 -> 사세요). In those, the ㄹ actually disappears sometimes. In our 르 rule, the ㄹ is growing, not shrinking. It is like the opposite of a diet. It is also different from ㄷ irregulars (like 걷다 -> 걸어요). While both involve the letter ㄹ, the starting point is different. The 르 rule is very specific to that 르 syllable. If you see 르, get ready for the double ㄹ party.