understructure

Definitions of understructure
  1. noun
    lowest support of a structure
    synonyms: base, foot, foundation, fundament, groundwork, substructure
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    types:
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    bed
    a foundation of earth or rock supporting a road or railroad track
    raft foundation
    a foundation (usually on soft ground) consisting of an extended layer of reinforced concrete
    railroad bed
    a bed on which railroad track is laid
    roadbed
    a bed supporting a road
    type of:
    support
    supporting structure that holds up or provides a foundation
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