How similar are the vocabularies of Thai, Lao, and Khmer?

Both Thai and Lao belong to the same language family, the Tai–Kadai language family. Khmer belongs to the Austroasiatic language family which is a different language family altogether. read more

Khmer comes from a different language family from Thai and Lao, but it borrowed heavily from Sanskrit for technical terms, and then Thai and Lao borrowed technical terms from Khmer, therefore those terms are in common between the three languages. read more

TL;DR: Thai, Lao and Khmer share a good amount of native vocabulary. Burmese does not share much native vocabulary with the other 3 languages. The four languages, however, do share a great deal of Pali vocabulary, as this is the liturgical language of Theravada Buddhism. read more

Thai and Lao are members of the Tai-Kadai language family. In fact, the two are quite similar, such that Thai and Lao are seen as languages in a Tai language ‘dialect continuum’ spanning from Thailand to southwest China. On the other hand, Khmer is part of the Mon-Khmer language family, linguistically related with neighboring Vietnamese. read more