Can you read this word?: 한여름 (middle of summer). It might look like it should be read as written, but it’s actually pronounced [한녀름].
Let’s look at a few more examples:
- 두통약 [두통냑] (headache pills)
- 담요 [담뇨] (blanket)
- 서른여섯 [서른녀섯] (thirty-six)
In Korean, this linguistic phenomenon is called ‘ㄴ-insertion (ㄴ-첨가).’
When a compound word has a front word ending a 받침, and the next word starts with the vowel /ㅣ/ or /ㅣ/ glide vowel like /ㅑ, ㅕ, ㅛ, ㅠ/, and invisible 니은 sneaks in!
While this specific explanation isn’t officially presented as an absolute linguistic rule in textbooks, here is how I understand it physically.
When you rush from the 받침 to the /ㅣ/ or /ㅣ/ glide vowels, your tongue naturally hits the roof of your mouth a bit wider, or lands halfway in between. Because it’s rooted in the natural movement of your mouth, everyday speech is often flexible:
- 그럼요 (Sure/Of course): [그럼요] or [그럼뇨]
- 바빴거든요 (Because I was busy): [바빧꺼든요] or [바빧꺼든뇨]
To be honest, my own tongue feels so much more comfortable pronouncing them as [그럼뇨] and [바빧꺼든뇨]. It actually takes extra effort for me not to pronounce that 니은 sound in between.