n. pl. ba·ses (-sēz′)
1. A fact or circumstance on which something is established: rumors with no basis in reality. See Synonyms at base1.
2. The chief constituent; the fundamental ingredient: The basis for most liquids is water.
3. The fundamental principle: Objective inquiry is the basis of science.
a. A pattern or schedule for proceeding: on a weekly basis.
b. A condition for relating or proceeding: a first-name basis; a friendly basis.
5. Archaic A physical base on which something rests.
[Middle English, foundation upon which something rests, base, from Latin, from Greek, a stepping, that on which one stands, base; see gwā- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 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.