English Words: O

15,494 words · Page 1 of 310

ocharacter

The fifteenth letter of the English alphabet, called o and written in the Latin script.

O'Brienname

A surname from Irish.

O'Callaghanname

A surname from Irish.

o'clockadv

In conjunction with a numeral, indicates the time within a twelve-hour period (midnight to noon or noon to midnight), specifically the time when the hour hand of a clock points precisely to the symbol or marking corresponding to the designated numeral, i.e., at the hour.

O'Connellname

A surname from Irish.

O'Connername

A surname from Irish.

O'Connorname

A patrilineal surname from Irish.

O'Deaname

A surname from Irish.

O'Dellname

A surname.

O'Dohertyname

A surname from Irish.

O'Donnellname

A surname from Irish.

O'Donoghuename

A surname from Irish; variant forms Donahue, Donoghue, Donohue, O'Donohue.

O'Donovanname

A surname from Irish.

O'Driscollname

A surname.

O'Dwyername

A surname from Irish.

O'Fallonname

A surname from Irish.

O'Flahertyname

A surname from Irish

O'Flynnname

A surname from Irish.

O'Garaname

A surname from Irish.

O'Gormanname

A surname from Irish.

O'Gradyname

A surname from Irish.

O'Keefename

A surname from Irish.

O'Keeffename

A surname from Irish.

O'Learyname

A surname from Irish.

O'Loughlinname

A surname from Irish.

O'Malleyname

A surname from Irish.

O'Maraname

A surname from Irish.

O'Mearaname

A surname from Irish.

O'Nealname

A surname from Irish, variant of O'Neill.

O'Neilname

A surname from Irish [in turn originating as a patronymic], a variant of O'Neill.

O'Neillname

A surname from Irish.

O'Reillyname

A surname from Irish [in turn originating as a patronymic] from Reilly.

O'Riordanname

A surname from Irish.

O'Rourkename

A surname from Irish.

o'snoun

plural of the letter o

O'Shaughnessyname

A surname from Irish.

O'Sheaname

A surname from Irish.

O'Sullivanname

A surname from Irish.

OAadj

Initialism of overacting.

oafnoun

A person, especially a large male, who is clumsy or a simpleton.

OAGnoun

Initialism of office of the attorney general.

Oahuname

The third-largest island of Hawaii, included in the City and County of Honolulu.

oaknoun

A deciduous tree with distinctive deeply lobed leaves, acorns, and notably strong wood, typically of England and northeastern North America, included in genus Quercus.

Oakdalename

A number of places in the United States:

Oakesname

A suburban area of Huddersfield, West Yorkshire, England (OS grid ref SE112341).

Oakhamname

A town and civil parish (with a town council) in and the county town of Rutland, England (OS grid ref SK8508).

Oaklandname

The eighth-largest city in California, United States, and the county seat of Alameda County.

Oakleighname

A suburb in south-east Melbourne, Victoria, Australia.

Oakleyname

Several places in England:

Oakridgename

A city in Lane County, Oregon, United States.

Spelling & Dictionary Insight

The English alphabetical index for the letter O contains 15,494 headwords drawn from our Wiktionary-derived dictionary table. At 50 entries per page the browse splits into 310 pages, and you are currently viewing page 1. 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.