n (mathematics) A definition of a mathematical object, up to isomorphism, in terms of abstract maps between it and other objects of the same category. More specifically, it is either the initial property of an initial object in a coslice category|coslice-like comma category or the terminal property of a terminal object in a slice category|slice-like comma category; these are roughly analogous to the minimum and the maximum (respectively) of a certain lattice, and are used to define the object uniqueness|uniquely up to isomorphism.