Sound Changes and Romanization — Why 종로 Is Jongno

Why spell by pronunciation

The Romanization of Korean is designed so that someone who does not know Korean can read the letters and come close to the Korean sounds. So Chapter 1, Article 1 takes standard pronunciation as its principle, and Chapter 3, Article 1 states that when a sound change occurs, the result of the change is written. If 종로 is written letter by letter as Jongro, a foreigner reads it "Jong-ro", but writing it Jongno after the actual sound [종노] comes much closer to how Koreans say it.

The regulation lists four sound changes to reflect and one not to reflect.

1. Assimilation between consonants

• Nasalization: Final ㄱ·ㄷ·ㅂ become ㅇ·ㄴ·ㅁ before ㄴ·ㅁ. 백마 [뱅마], 옷만 [온만] onman ("only clothes"), 입문 [임문] immun ("introduction").
• Nasalization of ㄹ: ㄹ after a final ㅁ·ㅇ becomes ㄴ. 종로 [종노], 대통령 [대통녕] daetongnyeong ("president"). ㄹ after a final ㄱ·ㅂ also becomes ㄴ, and that ㄴ in turn nasalizes the preceding final consonant. In 왕십리, the ㄹ after the ㅂ of 십 becomes ㄴ, and the ㅂ becomes ㅁ, giving [왕심니]. 독립문 [동님문] Dongnimmun and 속리산 [송니산] Songnisan go through the same process.
• Lateralization: When ㄴ and ㄹ meet, they are pronounced [ㄹㄹ], and ㄹㄹ is written ll. 신라 [실라] Silla, 별내 [별래] Byeollae, 설날 [설랄] seollal ("Lunar New Year").

신문로 has ㄴ meeting ㄹ, yet it is [신문노]. At the boundary of a compound such as 신문+로, ㄹ can turn into ㄴ instead (생산량 [생산냥], 의견란 [의견난]). This difference cannot be judged from spelling alone, so the converter keeps such words in a separate standard pronunciation dictionary.

2. When ㄴ or ㄹ is added

In a compound, when the first part ends in a consonant and the second begins with 이·야·여·요·유, a ㄴ is sometimes added (ㄴ insertion). 학여울 becomes [학녀울] and then, by nasalization, [항녀울]; in 알약 ("pill"), the added ㄴ turns into ㄹ after ㄹ, giving [알략] allyak. On the other hand, many words such as 금요일 [그묘일] ("Friday") take no added ㄴ, so this too needs a dictionary to be accurate. For words not in the dictionary, you can get the correct romanization by typing them as pronounced (e.g. 솜니불 instead of 솜이불, "cotton quilt").

3. Palatalization

Final ㄷ·ㅌ become ㅈ·ㅊ before a particle or suffix consisting of the vowel ㅣ. Writing 해돋이 ("sunrise") as haedodi or 같이 ("together") as gati is wrong. In 굳히다 ("to harden"), ㄷ and ㅎ first combine into ㅌ, which is then palatalized, giving [구치다]. 밭이 [바치] bachi ("the field" + subject particle) follows the same principle, while in 밭을 [바틀] bateul the following vowel is not ㅣ, so no palatalization occurs.

4. When ㄱ·ㄷ·ㅂ·ㅈ combine with ㅎ into aspirated sounds

ㄱ·ㄷ·ㅈ after a final ㅎ, or ㅎ after a final ㄱ·ㄷ·ㅂ·ㅈ, merge and are pronounced as the aspirated ㅋ·ㅌ·ㅍ·ㅊ, and are written that way. 착하다 [차카다] chakada ("to be kind"), 축하합니다 [추카함니다] chukahamnida ("congratulations").

However, in nouns, ㅎ following ㄱ·ㄷ·ㅂ is written out. The regulation's examples are 묵호 Mukho and 집현전 Jiphyeonjeon. Even though a noun like this is pronounced [무코], it is written Mukho, not Muko, to show its original form. 입학 iphak ("admission"), 국회 Gukhoe ("National Assembly") and 오죽헌 Ojukheon follow this rule.

So the same 축하 is chukha as a noun but chukahada in the verb 축하하다 ("to congratulate"). The converter's 'Auto-detect' treats a word as a verb or adjective, and writes the aspirated sound, when the next syllable is -히- or -혀- (passive/causative affixes) or is -하-, -해- and the like (forms of 하다) not at the end of the word. If it guesses wrong, choose 'Noun' or 'Verb/adjective' yourself in the options.

What is not reflected — tensing

Chapter 3, Article 1, Note states that tensing is not reflected in romanization.

Tensing is hard to predict, and writing it would produce many doubled letters such as kk and tt, which would actually make words harder to read. Of course, where the original spelling already has a tense consonant (꽃 in 벚꽃), it is written kk.

Not applied between words

Sound changes are reflected only within a single word. Between two words written with a space, such as 남산 타워, no assimilation is applied and each word is written on its own (Namsan Tawo). The converter also splits words at spaces.

Basis: Romanization of Korean, Chapter 1, Article 1; Chapter 3, Article 1 (items 1–4, Proviso and Note). Standard pronunciation follows the Standard Pronunciation Rules and the Standard Korean Language Dictionary. Checked 2026-09-23.

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