subsurface

[ suhb-sur-fuh s, suhb-sur- ]
/ sʌbˈsɜr fəs, ˈsʌbˌsɜr- /

adjective

below the surface, especially of a body of water.

Origin of subsurface

First recorded in 1770–80; sub- + surface
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

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