This research examines the words "dhu" and "dhat" meaning "possessor" and "owner" from the six nouns, and the two Tayyyat words as relative pronouns meaning "that which" and "that which" in Arabic grammar and the Holy Quran. These words are considered unique in the Arabic language and its grammar. The research stems from the importance of understanding the linguistic meaning of words, as they are tools for human communication and the linguistic interpretation of texts. Since the beginnings of linguistic study, Arab scholars have recognized the necessity of delving into the issues of word and meaning to serve the language of the Holy Quran and clarify its meanings. The first section of the research presents the linguistic origin of the words "dhu" and "dhat," their meanings, and their grammatical inflection in Arabic grammar. This is achieved through a study of the use of "dhu" as "possessor" and "dhat" as "owner," as they are among the six nouns. It also examines their use in the Tayy tribe language, meaning "that which" and "which." The second section focuses on the two words in the Holy Quran, exploring their various meanings, grammatical positions, and the number of times they appear. Their occurrence, along with an analysis of their Quranic contexts, reveals the breadth of their meaning, the subtlety of their style, and the beauty of the Quranic structure. Through this, the research seeks to highlight the grammatical and semantic dimensions of these words and clarify their impact on enhancing a precise understanding of Arabic texts in general, and the texts of the Holy Quran in particular, thus fulfilling the goal of linguistic study in serving comprehension and clarifying the grammatical and Quranic meaning for the reader.