The concepts of language and communication in the Qurʾān are articulated through a network of interrelated lexical items, including lafẓ (utterance), qawl (speech), lisān (tongue or language), bayān (expression), and kalimah (word), each of which carries a distinct semantic load within Qurʾānic discourse. Previous studies have typically examined these concepts either through isolated single term analyses or through comparisons restricted to a limited set of vocabulary, most commonly kalimah and qawl. The present study adopts a comprehensive and systematic approach by analyzing the semantic field of the central lexeme kalimah alongside all related lexical items in the same domain—namely lisān, lafẓ, qawl, bayān, and lugha. The significance of this investigation lies in moving beyond conventional grammatical definitions in order to uncover the deeper ontological dimensions of language within the logic of revelation. Using a descriptive analytical method, the study explains the rationale underlying the Qurʾān’s selective lexical usage and delineates the semantic boundaries of each term. The findings demonstrate that the absence of the term lugha in the Qurʾān to denote the concept of language—and its etymological connection to laghw (vain or meaningless speech)—reflects a deliberate and meaningful lexical choice. The analysis further shows that lexemes such as lafẓ, which denotes the sonic dimension of speech; lisān, which refers to the physical instrument of articulation; and qawl, which conveys the report or act of speech, represent more limited concepts that function within the broader semantic scope of kalimah. In the epistemic structure of the Qurʾān, kalimah therefore possesses semantic inclusiveness and conceptual dominance. Its essential meaning may be defined as the “manifestation of inner intention” (ibrāz mā fī al ḍamīr), encompassing a wide spectrum that extends from material speech to intellectual discourse, from ontological realities (ḥaqāʾiq takwīnīyah) to concrete entities such as the historical existence of Jesus Christ, and from communicative expression to revelatory speech. Accordingly, kalimah emerges as the most comprehensive communicative concept in the Qurʾān, providing the lexical foundation for the proposed theoretical framework known as the “Science of the Word” (ʿIlm al Kalimah).