In this article, using the approaches related to "critical discourse analysis" (CDA), the function of the word "Zindiq" (heretic) over time has been studied. Apparently, this word was used for the first time in Sassanid Pahlavi literature in the inscriptions of Cartier (Zoroastrian dogmatic priest) about the Manicheans who were oppressed and killed by this person. The word "Zindiq" was then used in Pahlavi, Arabic, and Persian literature to drive out and suppress ideological dissent. According to Foucault's classification of "exclusion" methods (in 1970), presumably, the derivation of "zand" to the Avestan root of zan-(to know) in "Zindiq" had been hidden by Zoroastrian priests in Sassanid period. In this study, it becomes clear that according to Fairclough (1995)'s three-layered model in discourse analysis and "intertextuality", relying on the texts of a period, the discourse function of words such as "Zindiq" is not understood or it is hardly possible to understand the discursive functions of this word in the texts of one area. It will also become clear that over time, Zandik's rejection of the discourse will expand, and that the leaders of any discourse, along with their followers, will often expel their opponents on Zandik charges in order to gain hegemony over their ideology. According to Laclau and Mouffe's (1985) theory of discourse, from during the juridical discourse of Sasanian period and later on, the new meanings were added to this word (Zindiq) by different "elements". Consequently, the function and meaning of "Zindiq" changed from “ interpreter of Avesta” to innovator (heretic), sinister, magician, etc. Thus, the implications of lexical jurisprudence are useless without CDA for understanding the meaning and function of "Zindiq".