Why does Khmer writing need subscripts?

In Unit 2, lesson 14, we introduced Khmer subscripts. Subscripts are used when combining two or more consonants to form a syllable. You might ask why English does not have subscripts and it can combined multiple consonants?

In order to explain why Khmer need subscripts, we have to back to our very first lesson where we introduce the first Khmer consonant KA, ក. The consonant ក ‘KA’ is written by itself without any vowel and form a word which mean ‘neck’ in English. This is a property in Khmer that English does not have. Khmer consonant by itself can make a syllable sound and can form a word. This is possible because each consonant can have an inherent vowel ‘OR’. So a consonant stands by itself without any vowel is assumed to have this inherent vowel ‘OR’. To indicate that multiple consonant need to combine as a syllable, subscript format is used.1.

As an example to illustrate this point, we can combine a few consonants in English and see how it can be written in Khmer. Let’s create an arbitrary syllable sound: ‘kla’. We combine consonant ‘K’ with another consonant ‘L’ then follow by a vowel ‘A’ making a syllable sound ‘kla’ (meaning ‘tiger’ in Khmer). An equivalent sound in Khmer would be the consonant ខ (‘KHA’) and consonant ល (‘LO’) follow by a vowel ា (‘A’). If we were to write them as all consonant and a vowel, it would read as two syllables ខ “KHOR” and លា “LEA”. But if we were to write consonant LO as a subscript, it tells us that KHA must combine with consonant LO as one syllable then follow by A which makes the sound ខ្លា (‘KLA’) as it sounds in English. As you can see without subscript, one English syllable can be read into two syllables for the Khmer equivalent arrangement without subscript.

It is possible to change the system so that the above case does not need to use a subscript. The above case can work similarly as English if we introduce the vowel ‘OR’ with some visible mark (let’s say a bar above the consonant) so you can identify if a consonant by itself ought to have a syllable sound (with a bar) or must combine with the next consonant.

Khmer subscript system does make the written language more condense. At the same time it becomes more complicated by double the number of consonant characters to learn. Mr. Keis Eav (អៀវ កើស) in his book ‘Khmer Language’ pointed out that this system creates difficulty in writing, printing, and learning. By creating one extra mark for this “OR” vowel we would be able to write similar like French without stacking using subscript. We would have reduce the number of characters and reduce the line spacing between each line of text. 2

Although there are other uses of subscript such as stacked syllable 3 where multiple syllables are condense using subscripts in Chapter 3 of unit 2 that this solution does not cover. After all, a system of writing of a language may not be all about simplicity. The intricacy and complexity of Khmer writing may have shown its rich cultural identity and history.


  1. There are some exception to many of Pali or Sanskrit word where two consonants are combined without using subscript. For example: វាសនា (VEASNA) means luck or fortune is read as [វាស-ស្នា ].
  2. Eav Keis. “Khmer Language: examination with reasons”. p32, 1967. Mit Serey Publishing.
  3. Stacked syllable such as បង្កើត, អង្គ្លេស. On the other hand, the stacked syllable can be written without stacking. In fact, many of them are written both ways. Example: អង្គ្លេស can also be written as អង់គ្លេស.