The Northeastern Thai vocabulary frequently found in the literature of early Ratanakosin Period was categorized into six parts of speech. The six parts of speech were Noun, Pronoun, Verb, Adjective, Preposition and Conjunction. The number of appearance of the six parts of speech was as follows: Verbs (160 words), Nouns (120 words), Adjectives (54 words), Pronouns (7 words), Prepositions (5 words) and Conjunction (1 words) respectively.