Definitions of structural:

• adjective:   relating to or having or characterized by structure

  Example: "Structural engineer"

• adjective:   relating to or caused by structure, especially political or economic structure

  Example: "Structural unemployment in a technological society"

• adjective:   concerned with systematic structure in a particular field of study
• adjective:   affecting or involved in structure or construction

  Example: "The structural details of a house such as beams and joists and rafters"

• adjective:   relating to or concerned with the morphology of plants and animals
• adjective:   pertaining to geological structure

  Example: "Structural effects of folding and faulting of the earth's surface"