word-forming element making adjectives from nouns, meaning "having, full of, having to do with, doing, inclined to," from Old French -ous, -eux, from Latin -osus (cf. -ose (1)). In chemistry, "having a lower valence than forms expressed in -ic."
Possessing; full of; characterized by: filamentous.
Having a valence lower than that of a specified element in compounds or ions named with adjectives ending in -ic: ferrous.