underlayer

From under- + layer.

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underlayer (plural underlayers)

1. A layer that is below another layer.

   Synonyms: substrate, substratum

2. (mining) A perpendicular shaft sunk to cut the lode at any required depth.^[1]
3. One who underlays.

underlayer (third-person singular simple present underlayers, present participle underlayering, simple past and past participle underlayered)

1. To form a layer beneath another

“underlayer”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.

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