The name Cambodia is derived from Khmer, the name of the people and the language. The word is best known because of the Khmer Rouge, the communist group which took control of the country in the 1970s and managed to kill off perhaps as much as a quarter of the nation's population before being expelled by the Vietnamese in 1979.
Rouge is the French word for red. The term simply means Communist Cambodia. Even within Cambodia the term is mispronounced as kuh-MARE when referring to the Khmer Rouge. Most foreigners pronounce it this way when referring to the people and the language, as well. And why not. That's the way it looks like it should be pronounced. Hold that thought.
Khmer is a tricky language to transliterate because it has more characters than any other alphabet. It has sixty distinct vowel sounds. There are sounds in Khmer that simply can not be written in English.
The language is closely related to Thai and Lao. The scripts look similar as well. Khmer characters are more dense and hard to read in my admittedly uneducated opinion. Thai and Lao scripts are more delicate and pleasing to the eye. For instance, this is the full name of Bangkok in Thai:
กรุงเทพมหานคร อมรรัตนโกสินทร์ มหินทรายุธยามหาดิลก ภพนพรัตน์ ราชธานีบุรีรมย์ อุดมราชนิเวศน์ มหาสถาน อมรพิมาน อวตารสถิต สักกะทัตติยะ วิษณุกรรมประสิทธิ์
This is a random bit of text in Khmer:
ក្រុមមន្រ្តីសុខាភិបាលនៃប្រទេសកម្ពុជា បានថ្លែងឱ្យដឹងកាលពីពេលថ្មីនេះថា ខ្លួននឹងចាប់ផ្តើមធ្វើការវ៉ាក់សាំងជំងឺរលាកសួតនិងរលាកស្រោម ខួរដល់ទារកនៅដំណាច់ខែមេសានេះជាអ្វីដែលខ្លួនអះអាងថា នឹងមានកុមារប្រមាណ៤០ម៉ឺននាក់ទទួលបានការចាក់នៅទូទាំងប្រទេស នេះ។
The latter just looks more cluttered to me. Note that there are no punctuation marks in Thai (or Khmer or Lao). The words all run together. This is a marked difference to what I've seen for the past few months. All words in Vietnamese are one syllable. The longest Vietnamese word I can think of is seven characters long. It uses Western-style punctuation. Here is a random bit of text in Vietnamese:
Luật Hiện đại hoá an toàn thực phẩm được giới thiệu tại Thượng viện, Luật này sẽ cải thiện những nổ lực của Chính phủ nhằm đảm bảo an toàn thực phẩm nhập khẩu và sản xuất trong nước.
None of this is to say I prefer Thai or Lao over Khmer (or Vietnamese). Quite the opposite. For some reason, even though they are closely related, Thai and Lao are tonal languages but Khmer is not. I am baffled by this. And yes, this is definitely another entry in the "Things That May Interest Only Me".
In tonal languages words that are spelled the same have different meanings depending on the tone of voice in which they are pronounced. Thai has four tones. Chinese has five. Vietnamese has six.
For example, "The new wood was not burnt, silk burnt," is translated in Thai as, "Mai mai mai mai mai mai." To say it properly you would say "Mai (with high tone), mai (with low tone), mai (with falling tone), mai (with falling tone), mai (with rising tone), mai (with falling tone)."
If you don't get the tones right, locals honestly have no idea what you're talking about. Here is a two-letter word with the six Vietnamese tones and their meanings.
mà but
má cheek
mả tomb
mã code
ma ghost
mạ rice seedling
If someone said in English "My house is haunted by a rice seedling" or "I planted a ghost" it would sound like gibberish. Vietnamese would experience the same confusion if you said ma instead of mạ. As one phrasebook I read said, it is difficult for Westerners to even hear the tones, let alone speak them correctly. It's incredibly frustrating.
I went off on this tangent to point out that this problem doesn't exist in Khmer. There are no tones. Although there are subtleties to pronunciation that are difficult for foreigners to pick up on, if you get close they are more likely to understand than they would be in Vietnam, for example.
It's in the transliteration that it becomes tricky. The best example is the word Khmer itself. It is not pronounced kuh-MARE. Whoever decided to spell it this way should be exhumed and beaten with a rubber hose. It is pronounced kh-ma-eh. Spoken quickly it sounds like kh-MY. Officially it's one syllable.
I don't understand why so many foreigners, and especially expats who have been in the country for years, persist in mispronouncing it. It's not hard to say it properly. Sometimes it's nearly impossible for non-native speakers to pronounce a foreign word. A common Vietnamese name is Nguyễn. If you're not Vietnamese it's unlikely you will ever say it properly. Is there a non-French speaker who can say trompe l'oeil (fool the eye) correctly?
Khmer is easy to say. Just say it correctly. It isn't pronounced the way it's spelled, but neither is Arkansas, Gloucester or Brisbane. I'm even more baffled by the mangling of Phnom Penh. It's pronounced p-NUM pen. Not hard. No one gets the second word wrong, but the first word is mispronounced more often than not. I can understand f-NOM since ph is pronounced as the letter f in English (and Vietnamese).
The most common mangling mystifies me. How does Phnom become Nom? The silent ph? This is particularly common among Brits and Aussies, but also among other foreigners and even Vietnamese.
Foreigners will always mispronounce the Vietnamese beach town of Nha Trang, which is not pronounced the way you might think just by looking at it. I was able to get around in Russian pretty well but I could never say Novosibirsk correctly. And so on. But saying Phnom Penh is not hard. If you say it incorrectly you are doing so deliberately. I find that somewhat disrespectful.