adj. thorn·i·er, thorn·i·est
1. Having many thorns or abounding in thorn-covered vegetation: thorny shrubs; a thorny landscape.
2. Spiny or prickly.
3. Controversial, problematic, or vexatious: avoided discussing thorny issues during the meeting.
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.