The paper reconstructs, using a historiographical an theoretical method, the essentially Trinitarian meaning of one of the most enigmatic divine names coined by Nicolaus Cusanus: non aliud. First, the author analyses the Trinitarian context in which the use of this expression arises, identifying its patristic and neo-platonic sources. After, on the basis of these acquisitions, he emphasizes the hermeneutic-speculative richness of this expression, which in his perspective, represents the climax of Cusanus' reflection on Deus Trinitas. Finally, he outlines the transcendence of the non aliud in relation to the Trinity by theoretically pairing it to the idea of the Beginning.