-ous

1. a suffix forming adjectives that have the general sense “possessing, full of ” a given quality ( covetous; glorious; nervous; wondrous ); -ous and its variant -ious have often been used to Anglicize Latin adjectives with terminations that cannot be directly adapted into English ( atrocious; contiguous; garrulous; obvious; stupendous ). As an adjective-forming suffix of neutral value, it regularly Anglicizes Greek and Latin adjectives derived without suffix from nouns and verbs; many such formations are productive combining forms in English, sometimes with a corresponding nominal combining form that has no suffix; Compare -fer, -ferous; -phore, -phorous; -pter, -pterous; -vore, -vorous.
2. a suffix forming adjectival correspondents to the names of chemical elements; specialized, in opposition to like adjectives ending in -ic, to mean the lower of two possible valences ( stannous chloride, SnCl 2 , and stannic chloride SnCl 4 ).

-ous

suffix forming adjectives

1. having, full of, or characterized by

   spacious

   languorous

   dangerous

2. (in chemistry) indicating that an element is chemically combined in the lower of two possible valency states Compare -ic

   stannous

   ferrous

Word History and Origins

Origin of -ous¹

Middle English < Anglo-French, Old French < Latin -ōsus; a doublet of -ose ¹

Word History and Origins

Origin of -ous¹

from Old French, from Latin -ōsus or -us, Greek -os, adj suffixes