1. Possessing; full of; characterized by: joyous.
2. Having a valence lower than that of a specified element in compounds or ions named with adjectives ending in -ic: ferrous.
[Middle English, from Old French -ous, -eus, -eux, from Latin -ōsus and -us, adj. suff.]
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.