Search Result for "direct sum":
Wordnet 3.0

NOUN (1)

1. a union of two disjoint sets in which every element is the sum of an element from each of the disjoint sets; 



WordNet (r) 3.0 (2006):

direct sum
    n 1: a union of two disjoint sets in which every element is the
         sum of an element from each of the disjoint sets