1. A community or territory over which a sovereign rules; a kingdom.
2. An area or sphere, as of knowledge or activity: the realm of science. See Synonyms at field.
[Middle English realme, from Old French, alteration (influenced by Old French reial, royal) of Latin regimen, government, from regere, to rule; see reg- 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.