n (mathematics) A collection τ of subsets of a set X such that the empty set and X are both members of τ and τ is closed under arbitrary unions and finiteintersections.
n (technology) The properties of a particular technological embodiment that are not affected by differences in the physical layout or form of its application.
n (context|topography) The topographical study of geographic locations or given places in relation to its history.
n (dated) The art of, or method for, assisting the memory by associating the thing or subject to be remembered with some place.