Architecture. the lowest part of a base, as of a column, that consists of two or more horizontal members.
Mathematics. a collection of subsets of a topological space having the property that every open set of a given topology can be written as the union of intersections of finite numbers of sets in the collection.Compare base1(def 13b).
Origin of subbase
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019