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 ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.