the monomorphemic word /naj/ in every period. It is found that the word /naj/ has 2 word categories, namely preposition and noun phrase connector. In addition, the word /naj/ has 10 grammatical meanings, namely the meaning “spatial relation”, “temporal relation...The purpose of this thesis is to analyze the word categories and the grammatical meanings of the word /naj/ from the Sukhothai to the present period and analyze the grammaticalization of the word /naj/ according to the concept of Heine and Kuteva

To collect and classify the function words in palm-leaf documents that developed from body-part and plant-part nouns in Lanna Thai. The factors and processes that motivate body-part and plant-part nouns to develop into classifiers, relative markers..., pronouns and prepositions are also studied. Body-part and plant-part nouns develop into 4 types of function words: classifiets, relative markers, pronouns and prepositions. As for the body-part nouns, 10 develop into classifiers, 3 into relative markers, 4