This paper examines the usage of the verb forms of hast in written colloquial Persian, focusing specifically on their non-emphatic copular meaning to analyze the reasons behind the widespread use of this function in colloquial Persian writing. Using the informal-formal corpus Aami, which includes over 50,000 sentence pairs, 868 occurrences of the forms hast, hastesh, and has were extracted as research data. The various uses of this verb in colloquial Persian were then analyzed and categorized. The findings show that in written colloquial Persian, the forms hast, hastesh, and has are used in different functions, including existential (indicating existence or presence) and emphatic copular (emphasizing the copula ast). Additionally, a third usage of this verb was observed, where it functions as a non-emphatic copula. This usage does not fit within conventional grammatical patterns but reflects speakers' tendencies toward using it. These changes can be interpreted as an example of the grammaticalization process of the verb boodan, particularly its third-person singular form hast. Grammaticalization principles such as layering and divergence, along with mechanisms like pragmatic inference and semantic bleaching, are instrumental in explaining this phenomenon. This process highlights the dynamism and adaptability of Persian in responding to speakers' communicative needs.

Keywords: Corpus-based, hast, ast, colloquial Persian, written colloquial Persian, grammaticalization