WordReference Random House Unabridged Dictionary of American English © 2026
un•der•stra•tum
(un′dər strā′təm, -strat′əm),USA pronunciation n., pl. -stra•ta (-strā′tə, -strat′ə),USA pronunciation -strat•ums.
- a substratum.
- under- + stratum 1725–35