-ous

• -ious, -tous, -uous

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).

• IPA^(key): /-əs/

• Audio (Southern England):

  (file)

-ous

1. 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

2. (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.

• -y
• (possession of): -ate

• -osity
• -ose

Note: Translations of English words ending in -ous do not necessarily end in the suffixes listed below.

• Sou, USO, U&Os, sou, OSU

• -os, -ose, -ouse, -ows, -owse, -us, -ws
• -ious; -uous (in some terms)
• -vous (in terms ending in /ˈeː/)

From Old French -ous, -us, -eus, from Latin -ōsus.

• IPA^(key): /-ˈuːs/, /-us/

-ous

1. Forms adjectives from nouns or verbs, especially if of Romance origin.

• Terms ending in /ˈeː/ usually take the variant -vous, as in beautevous, bountevous, deyntevous, plentevous from beaute, bounte, deynte, plente (but usually pitous or piteous, not pitevous). This was extended from Anglo-Norman bontivous (“virtuous”) and Old French plentivos (“plentiful”), which were formed from the pleonastic addition of -os to bontif and plentif, in turn formed from bonte and plente + -if; see -yf; then in Middle English, the analogy of bonte, plente : bontivous, plentivos allowed -(i)vous to be reinterpreted as a suffix, allowing for the creation of beautevous, deintevous, and pitevous, with the last remaining rare due to the influence of Old French piteos, pitos.
• As in Modern English, some terms take the variants -ious or -uous (e.g. rebellious, a variant of rebellous modelled on rebellioun). This must not be confused with the addition of -ous to terms already ending in -ie, -u, -ue, or -y, as in furious, melodious, or vertuous (from fury, melodie, vertu).

• English: -ous

• “-ǒus, suf.”, in MED Online, Ann Arbor, Mich.: University of Michigan, 2007.

-ous

1. alternative form of -us