op |ɑːp| — (law) Abbreviation of opinion.

op-ed |ˈɑpˌed| — simple past tense and past participle of ope

opacity |əʊˈpæsətɪ| — the phenomenon of not permitting the passage of electromagnetic radiation

opal |ˈəʊpl| — a translucent mineral consisting of hydrated silica of variable color; some varieties are used as gemstones

opalescent |ˌəʊpəˈlesnt| — having a play of lustrous rainbow colors

opaline |ˈəʊp(ə)liːn| — having a play of lustrous rainbow colors

opaque |əʊˈpeɪk| — hard or impossible to understand

opaqueness |əʊˈpeɪknəs| — incomprehensibility resulting from obscurity of meaning

ope |əʊp| — (now dialectal or poetic) Open. [from 13th c.]

open |ˈəʊpən| — a clear or unobstructed space or expanse of land or water

open up |ˈəʊpən ʌp| — cause to open or to become open

open-air |ˈəʊpənər| — in the open air

open-and-shut |ˈəʊpənər| — so obvious as to be easily solved or decided

open-ended |ˌəʊpən ˈendɪd| — without fixed limits or restrictions

open-eyed |ˌəʊpən ˈaɪd| — carefully observant or attentive; on the lookout for possible danger

open-faced |ˈəʊpnˈfeɪst| — (of a sandwich) Being a single slice of bread with a topping

open-handed |ˌəʊpən ˈhændɪd| — Generous; giving freely.

open-hearted |ˌəʊpən ˈhɑːrtɪd| — frank and candidly straightforward

open-minded |əʊpən ˈmaɪndɪd| — ready to entertain new ideas

open-mindedness  — Alternative form of open-mindedness.

open-mouthed |ˌəʊpən ˈmaʊðd| — Alternative form of open-mouthed.

open-source |əʊp(ə)nˈsɔːs| — of or relating to or being computer software for which the source code is freely available

open-work |ˈəʊpənwɜːk| — Alternative spelling of openwork.

opencast |ˈəʊpənkæst| — (of mines and mining) worked from the exposed surface

opened |ˈəʊpənd| — made open or clear

opener |ˈəʊpnər| — the first event in a series

opening |ˈəʊpnɪŋ| — an open or empty space in or between things

openly |ˈəʊpənlɪ| — in an open way

openness |ˈəʊpənnəs| — without obstructions to passage or view

openwork |ˈəʊpənwɜːk| — ornamental work (such as embroidery or latticework) having a pattern of openings

opera |ˈɑːprə| — a drama set to music; consists of singing with orchestral accompaniment and an orchestral overture and interludes

opera-glass |ˈɒpərəˌɡlɑːs| — A pair of small low-powered binoculars for use at a theatrical performance.

opera-glasses |ˈɒpərə ɡlæsɪz| — plural form of opera glass

opera-hat |ˈɒpərə hæt| — A kind of collapsible top hat.

opera-house |ˈɒpərə haʊs| — A theatre, or similar building, primarily used for staging opera.

operable |ˈɑːpərəbl| — fit or ready for use or service

operand |ˈɑːpərænd| — a quantity upon which a mathematical operation is performed

operant |ˈɑːpərənt| — having influence or producing an effect

operate |ˈɑːpəreɪt| — direct or control; projects, businesses, etc.

operated |ˈɑːpəˌretəd| — simple past tense and past participle of operate

operatic |ˌɑːpəˈrætɪk| — of or relating to or characteristic of opera

operating |ˈɑːpəˌretɪŋ| — being in effect or operation

operating-room |ˈɒpəreɪtɪŋrʊm| — a room in a hospital used for performing surgery

operating-theatre |ˈɒpəreɪtɪŋ θɪətər| — attributive form of operating theatre

operation |ˌɑːpəˈreɪʃn| — the state of being in effect or being operative

operational |ˌɑːpəˈreɪʃənl| — fit or ready for use or service

operationalize |ɒpəˈreɪʃ(ə)n(ə)laɪz| — To make operational.

operationally |ˌɑːpəˈreɪʃənlɪ| — in respect to operation

operative |ˈɑːpərətɪv| — a person secretly employed in espionage for a government

operator |ˈɑːpəreɪtər| — (mathematics) a symbol or function representing a mathematical operation

operetta |ˌɑːpəˈretə| — a short amusing opera

operose |ˈɒpərəʊs| — characterized by effort to the point of exhaustion; especially physical effort

ophidian |əʊˈfɪdiːən| — limbless scaly elongate reptile; some are venomous

ophiolatry |ɑːfiːˈɑːlətriː| — the worship of snakes

ophite |ˈɑːfaɪt| — (geology) Any of various rocks having snake-like markings, such as a mottled greenish porphyry. [from 16th c.]

ophthalmia |ɒfˈθælmɪə| — severe conjunctivitis

ophthalmic |ɑːfθælmɪk| — of or relating to ophthalmology

ophthalmologist |ˌɑːfθælˈmɑːlədʒɪst| — a medical doctor specializing in the diagnosis and treatment of diseases of the eye

ophthalmology |ˌɑːfθælˈmɑːlədʒɪ| — the branch of medicine concerned with the eye and its diseases

opiate |ˈəʊpɪət| — a narcotic drug that contains opium or an opium derivative

opine |əʊˈpaɪn| — express one's opinion openly and without fear or hesitation

opinion |əˈpɪnjən| — a personal belief or judgment that is not founded on proof or certainty

opinionated |əˈpɪnjəneɪtɪd| — obstinate in your opinions

opioid |ˈəʊpɪɔɪd| — A substance that is like opium.

opium |ˈəʊpɪəm| — an addictive narcotic extracted from seed capsules of the opium poppy

opodeldoc |ˌɑːpəˈdeldɑːk| — (obsolete) A kind of plaster, said to have been invented by Mindererus, used for external injuries.

opossum |əˈpɑːsəm| — small furry Australian arboreal marsupials having long usually prehensile tails

oppidan |ˈɑːpɪdən| — (rare) Of or pertaining to a town or conurbation.

oppo |ˈɒpəʊ| — (UK, informal) A friend, associate or colleague.

opponent |əˈpəʊnənt| — a contestant that you are matched against

opportune |ˌɑːpərˈtuːn| — suitable or at a time that is suitable or advantageous especially for a particular purpose

opportunely |ˈɒpətjuːnlɪ| — at an opportune time

opportuneness  — timely convenience

opportunism |ˌɑːpərˈtuːnɪzəm| — taking advantage of opportunities without regard for the consequences for others

opportunist |ˌɑːpərˈtuːnɪst| — a person who places expediency above principle

opportunistic |ˌɑːpərtuːˈnɪstɪk| — taking immediate advantage, often unethically, of any circumstance of possible benefit

opportunity |ˌɑːpərˈtuːnətɪ| — a possibility due to a favorable combination of circumstances

oppose |əˈpəʊz| — be against; express opposition to

opposed |əˈpəʊzd| — being in opposition or having an opponent

opposer  — someone who offers opposition

opposing |əˈpəʊzɪŋ| — characterized by active hostility

opposite |ˈɑːpəzət| — a word that expresses a meaning opposed to the meaning of another word, in which case the two words are antonyms of each other

opposition |ˌɑːpəˈzɪʃn| — the action of opposing something that you disapprove or disagree with

oppositional |ˌɑːpəˈzɪʃənl| — Of, pertaining to, or exhibiting opposition

oppositionist |ˌɒpəˈzɪʃənɪst| — A person who opposes; especially a member of an official opposition

oppress |əˈpres| — come down on or keep down by unjust use of one's authority

oppressed |əˈprest| — burdened psychologically or mentally

oppressing |əˈpresɪŋ| — Present participle of oppress.

oppression |əˈpreʃn| — the act of subjugating by cruelty

oppressive |əˈpresɪv| — weighing heavily on the senses or spirit

oppressiveness |əˈpresɪvnɪs| — a feeling of being oppressed

oppressor |əˈpresər| — a person of authority who subjects others to undue pressures

opprobrious |əˈprəʊbrɪəs| — expressing offensive reproach

opprobrium |əˈprəʊbrɪəm| — state of disgrace resulting from public abuse

oppugn |əˈpjuːn| — challenge the accuracy, probity, or propriety of

oppugnant |əˈpəɡnənt| — opposing, antagonistic, contrary

opt |ɑːpt| — select as an alternative over another

opt out |ˈɑːpt ˈaʊt| — choose not to do something, as out of fear of failing

optative |ˈɒptətɪv| — a mood (as in Greek or Sanskrit) that expresses a wish or hope; expressed in English by modal verbs

opted |ˈɑːptəd| — simple past tense and past participle of opt

optic |ˈɑːptɪk| — the organ of sight

optical |ˈɑːptɪkl| — of or relating to or involving light or optics

optically |ˈɑːptɪkəlɪ| — in an optical manner

optician |ɑːpˈtɪʃn| — a worker who makes glasses for remedying defects of vision

optics |ˈɑːptɪks| — the branch of physics that studies the physical properties of light

optimal |ˈɑːptɪməl| — most desirable possible under a restriction expressed or implied

optimally |ˈɑːptɪməlɪ| — in an optimal and most desirable way

optimism |ˈɑːptɪmɪzəm| — the optimistic feeling that all is going to turn out well

optimist |ˈɑːptɪmɪst| — a person disposed to take a favorable view of things

optimistic |ˌɑːptɪˈmɪstɪk| — expecting the best

optimistical |ˌɒptɪˈmɪstɪkəl| — optimistic

optimization |aptəməˈzeɪʃən| — the act of rendering optimal

optimize |ˈɑːptɪmaɪz| — make optimal; get the most out of; use best

optimum |ˈɑːptɪməm| — most favorable conditions or greatest degree or amount possible under given circumstances

option |ˈɑːpʃn| — the right to buy or sell property at an agreed price; the right is purchased and if it is not exercised by a stated date the money is forfeited

optional |ˈɑːpʃənl| — possible but not necessary; left to personal choice

optometrist |ɑːpˈtɑːmətrɪst| — a person skilled in testing for defects of vision in order to prescribe corrective glasses

optophone |ˈɑːptəfəʊn| — A device that transforms light into sound.

opulence |ˈɑːpjələns| — wealth as evidenced by sumptuous living

opulent |ˈɑːpjələnt| — ostentatiously rich and superior in quality

opus |ˈəʊpəs| — a musical work that has been created

opuscule |əʊˈpʌskjuːl| — A small or petty work.