a. Extremely aggressive or violent: a ferocious attack dog.
b. Characterized by or showing extreme aggressiveness or violence: a ferocious glare; ferocious claws.
2. Extremely powerful or destructive: a ferocious gale.
3. Extreme in activity or feeling; intense: a ferocious demand for a product; ferocious courage.
[From Latin ferōx, ferōc-, fierce; see ghwer- in the Appendix of Indo-European roots.]
fe·roci·ty (-rŏsĭ-tē), fe·rocious·ness n.
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.