1. Yielding or containing plenty; affording ample supply: a copious harvest. See Synonyms at plentiful.
2. Large in quantity; abundant: copious rainfall.
3. Abounding in matter, thoughts, or words; wordy: "I found our speech copious without order, and energetic without rules" (Samuel Johnson).
[Middle English, from Latin cōpiōsus, from cōpia, abundance; see op- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 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.