This paper analyzes Abū Bakr al-Bāqillānī’s (d. 1013) approach to the issue of the interpretability of language and the Qurʾān as presented in his books entitled Kitāb Iʿjāz al-Qurʾān and al-Taqrīb wal-Irshād. Al-Bāqillānī is known as the foremost Maliki jurist of his day and an Ash‘arī theologian who contributed to the major theological debates of the time. Despite his importance, his work on language and interpretability has received limited attention. In his texts on Qurʾānic inimitability and legal theory, he puts forth a unique interpretation of two Qurʾānic keywords—muḥkam and mutashābih—in the service of supporting his thesis that language is at once clear and multivalent. The terms muḥkam and mutashābih have a rich history in the Islamic interpretive tradition, beginning with early explanations of Qurʾān 3:7, where these terms are used. The scholars Leah Kinberg and Sahiron Syamsuddin have recently shown that explanations of Qurʾān 3:7 were the location of debates about whether humans can interpret the whole Qurʾān. To summarize a diverse range of positions, some scholars held that muḥkam verses had clear meanings and precluded non-literal interpretation, while mutashābih verses were considered ambiguous and not definitively comprehensible by humans. Others scholars argued that the whole Qurʾān is composed of muḥkam verses, meaning well-worded utterances, whereas mutashābih verses mutually confirm each other’s meanings. The positions scholars took on these terms are significant because they reflect their views on humans’ exegetical capacities and the legitimacy of non-literal interpretations. Scholarship has neglected al-Bāqillānī’s exegesis of these terms, a gap I address in this paper. I draw together al-Bāqillānī’s writings from two key genres in which he exerted influence—the doctrine of Qurʾānic inimitability and legal theory—in order to describe and analyze his explanation of what muḥkam and mutashābih mean. For al-Bāqillānī, the whole Qurʾān and many (perhaps all) human-authored utterances are muḥkam, which he takes to mean clear and internally consistent. Many utterances are also mutashābih, meaning multivalent, expressing more than one meaning at once. By redefining key terms in this way, al-Bāqillānī builds a semantic field to describe language as systematic and wholly interpretable. This tactic in turn helps him establish language as a reliable and stable means of communicating law and theology. This paper contextualizes these positions and argues that al-Bāqillānī’s reframing of Qurʾānic terms constitutes an important contribution to Islamic discourse on interpretability.