-ous

See also: ous and -ouš

Alternative forms

-ious, -tous, -uous

Etymology

From Middle English -ous, from Old French -ous, -os, -us, from Latin -ōsus (“full of”). Doublet of -ose and -wise in unstressed position. Many English adjectives ending in -ous were taken from preexisting French or Latin adjectives that end in one of the above suffixes (e.g. envious corresponds directly to Old French envious which in turn corresponds directly to Latin invidiōsus). In addition, -ous (or the variant form -ious) has at times been attached to English nouns to form derived adjectives that lack precedents in French or Latin, such as slumberous from slumber or blizzardous from blizzard. It has also been used in some cases as a means of adapting adjectives borrowed from Latin that originally ended simply in -us, -a, -um (for example, obvious and previous are derived from Latin obvius and praevius, not *obviōsus or *praeviōsus).

Pronunciation

IPA^(key): /-əs/
Audio (Southern England): (file)

Suffix

-ous

Used to form adjectives from nouns, to denote:
1. possession of
  ‎bulb + ‎-ous → ‎bulbous
2. presence of a quality in any degree (typically an abundance)
  ‎courage + ‎-ous → ‎courageous
  
  ‎joy + ‎-ous → ‎joyous
  
  ‎poison + ‎-ous → ‎poisonous
  
  ‎riot + ‎-ous → ‎riotous
3. relation or pertinence to
  ‎aptonym + ‎-ous → ‎aptonymous
  
  ‎arrhenotoky + ‎-ous → ‎arrhenotokous
(chemistry) Used in chemical nomenclature to name chemical compounds in which a specified chemical element has a lower oxidation number than in the equivalent compound whose name ends in the suffix -ic. For example sulphuric acid (H₂SO₄) has more oxygen atoms per molecule than sulphurous acid (H₂SO₃). See Inorganic nomenclature.