absolute, in philosophy, the opposite of relative. The term has acquired numerous widely variant connotations in different philosophical systems. It means unlimited, unconditioned, or free of any relation; perfect, complete, or total; permanent, inherent, or ultimate; independent, or valid without reference to a perceiving subject. In epistemology, absolute means certain or indubitable as opposed to probable or hypothetical. As a substantive, the absolute is the ultimate basis of reality, the principle underlying the universe. Theologically, it is synonymous with, or characteristic of, God. Philosophically, it may be considered as the unknowable, the thing-in-itself; as that ultimate nonrelative that is the basis of all relation; as the ultimate, all-comprehensive principle in which all differences and distinctions are merged. The concept of the absolute was present in Greek philosophy. In modern times, both realists and idealists have used the term, but it is, perhaps, most intimately connected with the idealism of G. W. Hegel.