la·bo·ri·ous  (l ə-bôr ē- əs)
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adj.1. Marked by or requiring long, hard work: spent many laborious hours on the project. 2. Hard-working; industrious.
[Middle English, from Old French laborieux, from Latin labōriōsus, from labor, labor.]
la·bori·ous·ly adv. la·bori·ous·ness n. |
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:
Indo-European Roots
Semitic Roots
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.
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