sub·stra·tum (sŭbstrā′təm, -străt′əm)
n. pl. sub·stra·ta(-strā′tə, -străt′ə) or sub·stra·tums
a. An underlying layer.
b. A layer of earth beneath the surface soil; subsoil.
2. A foundation or groundwork.
3. The material on which another material is coated or fabricated.
4. Philosophy The underlying characterless substance that supports attributes of material reality.
5. Biology A substrate.
6. Linguistics A substrate.
[New Latin substrātum, from neuter of Latin substrātus, past participle of substernere, to lay under : sub-, sub- + sternere, to stretch, spread; see ster-2 in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.