understratum

[ uhn-der-strey-tuh m, -strat-uh m ]
/ ˈʌn dərˌstreɪ təm, -ˌstræt əm /
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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.

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. 2019

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