The majority of Cambodians, even those who are not ethnic Khmer, speak Khmer, the official language of the country.

Ethnic Khmer living in Thailand, in Vietnam, and in Laos speak dialects of Khmer that are more or less intelligible to Khmer speakers from Cambodia. Minority languages include Vietnamese, Cham, several dialects of Chinese, and the languages of the various hill tribes. Khmer, in contrast to Vietnamese, Thai, Lao, and Chinese, is notional. Native Khmer words may be composed of one or two syllables. Khmer has a rich system of affixes, including infixes, for derivation. Generally speaking, Khmer has nouns, verbs, adverbs, and various kinds of words called particles.

The normal word order is subject-verb-object. Khmer uses Sanskrit and Pail rots much as English and other West European languages use Latin and Greek roots to derive new, especially scientific, words. Khmer has also borrowed terms – especially financial, commercial, and cooking terms – from Chinese, French, and English as well.

These latter borrowings have been in the realm of material culture, especially the names for items of modern Western technology. The language has symbols for thirty-three consonants, twenty-four dependent vowels, twelve independent vowels, and several diacritics.