The principle of iṭlāq (absoluteness) is a fundamental verbal principle in Islamic legal theory that uncovers the speaker's true intent when there is doubt about potential restrictions in speech, and its authority rests upon rational custom (bināʾ al-ʿuqalāʾ) and its endorsement by the Lawgiver. Employing a descriptive‑analytical method, this article first elucidates the theoretical foundations of this principle from the perspectives of Imam Khomeini and seven prominent scholars (Anṣārī, Khurāsānī, Nāʾīnī, Muẓaffar, Khūʾī, Ṣadr, and Āshtiyānī). It then analyzes its concrete applications in six cases from his five‑volume work al‑Bayʿ, including the binding nature of muʿāṭāt, khiyār al‑majlis, the loss of countervalues, liability for hunting in iḥrām, and the distinction between prescriptive and constitutive prohibitions. Subsequently, drawing upon rational custom and customary practice, the study explores the scope of this principle in contemporary emerging transactions such as cryptocurrencies, the sale of human organs, and contracts involving data, patents, and franchises. The findings indicate that Imam Khomeini, through his precise distinction between the principle of generality (ʿumūm) and absoluteness (iṭlāq), and his reliance on the preliminaries of wisdom (muqaddimāt al‑ḥikma), offers an innovative approach fully aligned with customary practice—further reflected in his theory of gradual linguistic convention (al‑waḍʿ al‑takwīnī). The conclusion is that the principle of iṭlāq, as a rational and sharʿī instrument—while respecting its limitations (e.g., doubts in application and the presence of specific evidence)—can effectively fill the normative gaps of modern financial systems and ensure the dynamism of contemporary jurisprudence.