English Words: O

1,431 words · Page 14 of 29

operationsnoun

plural of operation

operativeadj

Effectual or important.

operativelyadv

In an operative manner.

operatornoun

A person or organisation that operates a device, system, service, etc.

operatorsnoun

plural of operator

operculumnoun

A covering flap in animals, such as a gill cover.

operettanoun

A lighter version of opera with a frivolous story and spoken dialogue.

operonnoun

A unit of genetic material that functions in a coordinated manner by means of an operator, a promoter, and structural genes that are transcribed together.

Ophelianame

A female given name from Ancient Greek.

Ophirname

A city or region mentioned in the Bible, famous for its gold.

ophthalmicadj

Of or pertaining to the eyes.

ophthalmologistnoun

A medical doctor specializing in the eye: deficiencies of vision requiring correction, and diseases. Compare optometrist.

ophthalmologynoun

The anatomy, functions, pathology, and treatment of the eye.

OPInoun

Initialism of office of primary interest.

opiateadj

Relating to, resembling, or containing opium.

Opiename

A surname from Cornish.

opineverb

To express an opinion; to state as an opinion; to suppose, consider (that).

opiningnoun

The act of giving one's opinion.

opinionnoun

A belief, judgment or perspective that a person has formed, either through objective or subjective reasoning, about a topic, issue, person or thing.

opinionatedverb

simple past and past participle of opinionate

opinionsnoun

plural of opinion

opioidnoun

A substance that has effects similar to opium:

opiumnoun

A yellow-brown, addictive narcotic drug obtained from the dried juice of unripe pods of the opium poppy, Papaver somniferum, and containing alkaloids such as morphine, codeine, and papaverine.

OPMname

Initialism of Office of Personnel Management.

Oportoname

Synonym of Porto (“city in Portugal”).

opossumnoun

Any American marsupial of the family Didelphidae in the order Didelphimorphia.

oppprep

Abbreviation of opposite.

oppanoun

An affectionate term of address for an older brother or somewhat older man.

Oppenheimname

A surname from German.

Oppenheimername

A surname from German.

opponoun

A friend, associate or colleague.

opponentnoun

One who opposes another; one who works or takes a position against someone or something; one who attempts to stop the progress of someone or something.

opportuneadj

Suitable for some particular purpose.

opportunismnoun

The practice of taking advantage of any situations or people to achieve an end, often with no regard for principles or consequences.

opportunistnoun

Someone who takes advantage of any opportunity to advance their own situation, placing expediency above principle.

opportunisticadj

Taking advantage of situations that arise.

opportunisticallyadv

In an opportunistic manner.

opportunitiesnoun

plural of opportunity

opportunitynoun

A chance for advancement, progress or profit.

opposableadj

Susceptible to being opposed or resisted.

opposeverb

To attempt to stop the progression of; to resist or antagonize by physical means, or by arguments, etc.; to contend against.

opposedadj

Acting in opposition; opposing.

opposingadj

That opposes or oppose; on the opposite side.

oppositeadj

Located directly across from something else, or from each other.

oppositelyadv

In an opposite manner.

oppositionnoun

The action of opposing or of being in conflict.

oppositionaladj

Of, pertaining to, or exhibiting opposition.

oppressverb

To keep down by unjust force.

oppressedadj

Subject to oppression.

oppressionnoun

The exercise of authority or power in a burdensome, cruel, or unjust manner.

Spelling & Dictionary Insight

The English alphabetical index for the letter O contains 1,431 headwords drawn from our Wiktionary-derived dictionary table. At 50 entries per page the browse splits into 29 pages, and you are currently viewing page 14. Every row above is a dictionary-backed entry with a canonical slug, and each links through to a full definition page with pronunciation, senses, etymology, and related-word data where available.

On this page 50 of 50 entries carry a part-of-speech tag and 50 carry at least one stored definition. Coverage varies across letters because Wiktionary volunteers build entries at different speeds for different parts of the alphabet, letters with common starting sounds (S, C, T, P) usually have the densest coverage, while less frequent starters (X, Q, Z) tend to have shorter but more specialised lists. PlainSpell surfaces whatever data is present and links back to the source when a definition is not yet recorded.

For readers using this index as a spelling reference, the guarantee is that every form you see on the list is a documented English headword, not a guess, not a derived inflection lacking a lemma row. If a word you expected to find is absent from the "O" list, it usually means the form exists only as an inflection of another lemma (e.g. a past participle stored under the infinitive) or the entry has not yet been imported from Wiktionary. Use the search bar or the misspelling lookup to resolve these cases.