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understratum

[uhn-der-strey-tuh m, -strat-uh m]
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noun, plural un·der·stra·ta [uhn-der-strey-tuh, -strat-uh] /ˈʌn dərˌstreɪ tə, -ˌstræt ə/, un·der·strat·ums.
  1. a substratum.

Origin of understratum

First recorded in 1725–35; under- + stratum
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for understratum

Historical Examples

  • Where the city is now built it is fine siliceous sand, supported by an understratum of clay, which is of varied colors.

    Petals Plucked from Sunny Climes

    Sylvia Sunshine

  • But there is an understratum of deep, calm sea, which the breath of the wildest tempest can never reach.