They call their language Kham Mueang in which Kham means language or word; mueang; town, hence the meaning of "town language," specifically in contrast to those of the many hill tribe peoples in the surrounding mountainous areas.
Their language is called Kham Mueang, derived from the words meaning "language" and "town", hence specifically denoting a local dialect as opposed to those of the various hill tribes inhabiting the nearby mountains.