Definition of underclay Underclay
un•der•clay
We found 3 definitions of underclay from 3 different sources.
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What does underclay mean?
Wiktionary 
- underclay (Noun)
A stratum of clay lying beneath a coal bed.
Webster DictionaryWebster's Unabridged Dictionary 📘
- underclay (n.)
A stratum of clay lying beneath a coal bed, often containing the roots of coal plants, especially the Stigmaria.
Chambers DictionaryChamber's 20th Century Dictionary 📕
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underclay
un′dėr-klā, n. the bed of clay almost always found under coal-seams, considered as the soil in which grew the plants that formed the coal
