Essential Greek and Latin Roots for Twelfth Grade Students: or, os

Learn these words that derive from the Latin noun os, "mouth," and the Latin verb orare, "to plead; to ask for."
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Full list of words from this list:

words only definitions & notes
  1. oral
    of or relating to or affecting or for use in the mouth
    Not taking care of your teeth impacts more than your oral health, however. US News (May 20, 2015)
    os + al (suffix forming adjectives)
    Oris in Latin is the possessive form of os, "mouth"; hence many derivatives come from its stem, or.
  2. orotund
    full and rich, of sounds
    He pitched his orotund voice upon me as if he were giving a command in a gale at sea. Ward, Herbert D. (Herbert Dickinson)
    os + rotundus ("round")
    This word derives from a two-word Latin phrase meaning "with round mouth." Rounding one's mouth helps to produce full and rich sounds.
  3. orifice
    an opening, especially one that opens into a bodily cavity
    We live in a microbial world: Trillions of different bacteria colonize our skin, gut, and orifices. Scientific American (Dec 17, 2017)
    os + facere ("to make or do")
  4. osculation
    the act of kissing
    A mutual kiss here counts as two osculations. Dudeney, Henry Ernest
    os + culum (suffix forming diminutives) + ation (suffix forming nouns)
  5. oscillate
    be undecided about something
    I weighed my options, oscillating back and forth. Time (Oct 29, 2014)
    os + culum (suffix forming diminutives) + ate (suffix forming verbs)
    Etymologically, this word is closely related to osculate, but in modern usage oscillate no longer has a literal connection to the mouth. The verb comes from the ancient belief that hanging an open-mouthed mask of Bacchus, the god of wine, would help vineyards. The sense of indecision comes from the mask swinging in the breeze.
  6. oscillation
    a complete execution of a periodically repeated phenomenon
    For Chalmers, the easy part of consciousness entails mapping exactly what the brain is doing, whether it is oscillations in the cerebral cortex or re-entrant loops in the thalamocortical system. The Guardian (Jun 19, 2018)
  7. orator
    a person who delivers a speech
    I’ll never be an orator, but anyone can learn to get up and speak. The Guardian (Oct 17, 2014)
    orare ("to speak") + or (suffix forming nouns)
    The noun orator, "public speaker," is a direct borrowing from Latin. It derives from the verb form oratus (past participle of orare) meaning "having been spoken."
  8. oratory
    the act of addressing an audience formally
    Douglass rode his talent for soaring oratory to the top ranks of the abolitionist movement and embraced other radical reform campaigns along the way. Washington Post (Feb 18, 2019)
    orare + ory (suffix forming adjectives or nouns)
  9. oratorio
    a musical composition for voices and orchestra
    The oratorio ends with the chorus singing, “Greater love has no man than he who gives his life for those he loves.” New York Times (Jun 4, 2015)
    orare + ory (suffix forming adjectives or nouns)
  10. oracle
    an authoritative person who divines the future
    Instead I knelt on the floor, feeling like a pilgrim begging advice from an all-knowing oracle. Miss Peregrine's Home for Peculiar Children
    orare + culo (suffix forming nouns designating "places or instruments")
    The noun oracle can refer to the person who predicts the future, the shrine where one consults a god who knows the future, or the prophecy itself.
  11. orison
    reverent petition to a deity
    He started his orisons again, and soon was praying like a locomotive: “Ora pro nobis! Stocking, Charles Francis
    orare + ion (suffix forming nouns)
Created on Wed Jun 18 11:57:24 EDT 2025

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