Previous studies show that Thai people’s ways of life and traditions from birth to death are related to ghosts. Most of the studies deal with the role of ghosts in Thai society but there has been no study on ghost terms in Thai, which would reflect the ghost system in Thai thoughts. Thus, this study aims to analyze the system and categorization of terms for ghosts and spirits in Thai. Folk taxonomy, which is a method in the ethnosemantic approach, has been adopted for the analysis. 

Data elicitation of the meanings of Thai ghost terms was done at Wat Suan Kaew Community, Tambon Bang Len, Amphoe Bang Yai, Nonthaburi Province, as representative of the mainstream Thai community. Fifteen intentionally selected informants were interviewed. The result of the analysis shows that there are forty nine categories of ghosts and spirits in Thai. They are classified into a taxonomy of five hierarchical classes: unique beginner, life-form, generic, specific, and varietal. There is only one unique beginner term:‘ghost+spirit’. There are two life-form terms: ‘ghost’ and ‘spirit’. As for generic ghost terms under life form, there are seven. Thirty three specific ghost terms were found e.g. ‘female spirit of a tree’’, ‘forest demon’, ‘evil tall spirit’, etc. There are eight sub-specific or varietal ghost terms, such as ‘female banyan tree spirit’, ‘female tamarind tree spirit’, ‘female banana tree spirit’, etc. 

It should be noted that Thai people conceive of ghosts as human. Indeed, most types of ghosts have a human shape and some are even human themselves. Thai ghosts are distinguished by their kindness or badness, sex, age, dwelling place and the food they take. 

Furthermore, it has been found that Thai people have negative attitudes towards ghosts as can be seen from the meanings of ghost terms. They find ghosts frightening, disgusting, susceptible to bribes or dogged with misfortune as a result of karma. However, ghosts are seen as a means of controlling society.