[1] : The Collaborative International Dictionary of English v.0.48

substructure \substruc"ture\, n. pref. sub- + structure.
   1. arch. same as substruction.
      1913 webster

   2. an under structure; a foundation; groundwork.
      1913 webster
see also:
substruction 

[2] : WordNet (r) 2.0

substructure
     n 1: the basic structure or features of a system or organization
          syn: infrastructure
     2: lowest support of a structure; "it was built on a base of
        solid rock"; "he stood at the foot of the tower" syn: foundation,
         base, fundament, foot, groundwork, understructure
see also:
infrastructure foundation base fundament foot groundwork 
understructure 

[3] : Moby Thesaurus II by Grady Ward, 1.0

41 moby thesaurus words for "substructure":
   base, basement, basis, bearing wall, bed, bedding, bedrock, bottom,
   floor, flooring, fond, footing, foundation, fundament, fundamental,
   ground, grounds, groundwork, hardpan, infrastructure, pavement,
   principle, radical, riprap, rock bottom, rudiment, seat, sill,
   solid ground, solid rock, stereobate, stylobate, substratum,
   substruction, terra firma, underbuilding, undercarriage,
   undergirding, underpinning, understruction, understructure

Substructure >> S Words
Substructure, definition of term: Substructure
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