originatornounSomeone who originates, creates or founds something.
OrillianameA city in northern Simcoe County, Ontario, Canada.
OrinoconameA South American river flowing 1600 miles (2410 km) from Brazil through Venezuela to the Atlantic Ocean.
oriolenounAny of various colourful passerine birds, New World orioles of the genus Icterus (family Icteridae) and Old World orioles of the family Oriolidae.
OriolesnameThe team Baltimore Orioles.
OrionnameA giant-hunter, pursuer of the Pleiades and lover of Eos, and killed by Artemis.
OrissanameFormer name of Odisha: A state in eastern India.
OriyanameOdia, the language spoken in the state of Odisha, India.
OrkneynameEllipsis of Orkney Islands.
OrlanameA female given name from Irish.
OrlandonameA male given name from Italian.
OrleansnameA city, the capital of Loiret department, France; the regional capital of Centre-Val de Loire.
OrlovnameA surname from Russian.
OrlynameA city and commune of the department of Val-de-Marne, region of Île-de-France, France.
OrmenameA surname from Old Norse.
OrmsbynameA surname from Old Norse.
OrmskirknameA market town in West Lancashire district, Lancashire, England (OS grid ref SD4108).
ornverbTo ornament; to adorn.
ornamentnounAn element of decoration; that which embellishes or adorns.
ornamentaladjServing as an ornament; having no purpose other than to make more beautiful.
ornateadjElaborately ornamented, often to excess.
OrnenameA department of Normandy, France.
orneryadjDisagreeable, stubborn, and troublesome to deal with; cantankerous.
ornithologynounThe branch of zoology that deals with the scientific study of birds.
orogenicadjConcerned with orogeny; pertaining to the creation of mountains.
orogenynounThe process of mountain building by the upward folding of the Earth's crust.
OromonounA member of a people of eastern Africa, Ethiopia and northern Kenya.
oropharyngealadjOf or pertaining to both the mouth and the pharynx.
OrovillenameA city, the county seat of Butte County, California, United States.
orphannounA person, especially a minor, both or (rarely) one of whose parents have died.
orphanagenounA residential institution for the care and protection of orphans.
orphanedadjMade an orphan by the death of one's parents.
OrpheusnameA Thracian musician and poet, who failed to retrieve his wife Eurydice from Hades.
OrpingtonnameA town in the borough of Bromley, Greater London, southeastern England (OS grid ref TQ4666).
OrrnameA Scottish surname.
orrerynounA clockwork model of any given solar system.
OrrinnameA male given name from Irish of obscure origin, possibly a variant of Oren or Oran.
Orsnounplural of other (others) used in case citations.
ortnounA fragment; a scrap of leftover food; any remainder; a piece of refuse.
OrteganameA surname from Spanish.
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 18. 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.