In this paper I analyze the notion of absolute concept in the thought of Nicolas de Cusa. This notion attributed to God reveals the uni-trinity understood as reflection, thought of thought or definition that defines itself. Cusanus conceives this by using the model of human subjectivity and poses an absolute grammar that the mind explains as actualization of its possibilities. In this way, the correspondence between reality and thought typical of Neoplatonism and idealism has singular notes in cusan philosophy.