-ous

Etymology

It is inherited from Middle English -ous,^[2][3][1] borrowed from Anglo-Norman -ous, also -os and -us,^[4][5][6] and Old French -ous,^[2][7][3][1] from Latin -ōsus (“abounding in, full of”),^[4][7][5][8] as in cōpiōsus, fāmōsus and glōriōsus.^[4] Merriam-Webster also sees the plain ending -us of adjectives such as fatuus,^[3] which the American Heritage Dictionary and Collins include,^[2][9] and Klein compares Ancient Greek -ος (-os).^[8] It is a doublet of -ose.^[1][10]

Earliest recorded meaning

The earliest English words with the suffix came from Anglo-Norman or Old French adjectives in the 13th century, such as dangerous and orgulous,^[4] and there were also older Norman forms such as coveitos and coveitus, covetous.^[5][4]

Semantic evolution

The long Latin vowel became a diphthong in early Old French, and in Central French it went on to give the modern ending French -eux.^[4] English took the Anglo-Norman forms and identified the vowel with Middle English long u, hence the spelling -ous, though the sound has weakened to /əs/.^[4] This -ous became the regular form for all later adoptions from French or Latin, and for new words on the same pattern, native bases included.^[4][5] English also went further than French or Latin, turning the suffix into the ordinary way of anglicizing Latin adjectives of many kinds, as with aqueous, atrocious, nefarious, stupendous and garrulous.^[4][5] Related nouns end in -osity.^[5] In chemistry it marks a lower valence than the corresponding word in -ic, as with ferrous beside ferric.^[9][3][7]

Timeline

• 13th century – dangerous, orgulous, from French.^[4]
• 14th century – adventurous, courageous, joyous; first new formations in English, guilous, noyous.^[4]
• 15th century – melodious, pompous from French, slumberous, tyrannous formed in English, and numerous, obsequious from Latin.^[4]
• 16th century – murderous, poisonous, thunderous.^[4]
• 18th century – felicitous, delirious.^[4]
• 19th century – glamorous.^[4]
• 20th century – pulchritudinous, serendipitous.^[4]

Meanings

Suffix

1. Forming adjectives meaning having, full of or characterized by something: hazardous, spacious.^[9][3][6]
2. Forming adjectives meaning having the nature of or inclined to something: mountainous, rebellious.^[6][11]
3. (chemistry) Marking an element in the lower of two valence states: cuprous, stannous.^[9][3][4]

Word family

• famous
• glorious
• dangerous
• joyous
• poisonous

Related words

• -ose
• -ic

References

1. ^ a b c d Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
3. ^ a b c d e f Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
4. ^ a b c d e f g h i j k l m n o p q Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
5. ^ a b c d e f Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
6. ^ a b c Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
7. ^ a b c Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
8. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
9. ^ a b c d Collins English Dictionary (2023), Glasgow: HarperCollins
10. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
11. ^ Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology