-ous

American  

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;

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 SnCl4 ).

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-ous British  

suffix

1. having, full of, or characterized by

   dangerous

   spacious

   languorous

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

   ferrous

   stannous

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Etymology

Origin of -ous

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

Example Sentences

Scabrose -ous: rough like a file, with small raised points.

From Explanation of Terms Used in Entomology by Smith, John. B.

Compare the English capacious, veracious, hilarious, where -ous is added to other stems than those in o.

From Society for Pure English Tract 4 The Pronunciation of English Words Derived from the Latin by Sargeaunt, John

Bisetose -ous: with two bristle-like or setaceous appendages.

From Explanation of Terms Used in Entomology by Smith, John. B.

An acid terminating in -ous forms a salt ending in -ite, and an oxyacid ending in -ic forms a salt ending in -ate.

From Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" by Various

The most familiar one of these is given a name ending in the suffix -ic, while the one with less oxygen is given a similar name, but ending in the suffix -ous.

From An Elementary Study of Chemistry by McPherson, William