understratum

[ uhn-der-strey-tuhm, -strat-uhm ]

noun

, plural un·der·stra·ta [uhn, -der-strey-t, uh, -strat-, uh], un·der·strat·ums.

1. a substratum.

Word History and Origins

Origin of understratum¹

First recorded in 1725–35; under- + stratum

Example Sentences

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

From Project Gutenberg

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

From Project Gutenberg