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PlainSpell

o

/ˈoʊ/letter, number, noun, interjection, adjective, preposition

o is spelled O: one letter and one syllable. It appears 132 times per million words in written English, the 792nd most frequent word form (wordfreq, 2021 data). As a letter, o means “The fifteenth letter of the English alphabet, called o and written in the Latin script” (English Wiktionary, September 2026).

How many letters and syllables are in o?

Letters1: O
Syllables1 (from its American pronunciation)
In writing132 times per million words; the 792nd most frequent word form
Wrong spellings searchednone measured in search
Sounds like
Rhymes with

Sources: letters and syllables from the English Wiktionary's hyphenation or pronunciation and the CMU Pronouncing Dictionary; written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media); rhymes and same-letter words are computed by PlainSpell from its own word list.

How common is o?

O appears 132 times per million words in written English, the 792nd most frequent word form in the list.

Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).

How do you pronounce o?

  • UK /ˈəʊ/
  • US /ˈoʊ/

O has one syllable (counted from its American pronunciation in the CMU Pronouncing Dictionary).

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: En-uk-o.ogg, En-us-o.ogg, LL-Q1860_(eng)-Vealhurl-o'.wav, Wikimedia Commons (author and licence on each file's page).

Words people confuse with o

Sounds like: oh, owe (Wiktionary's homophone list; some hold only in some accents).

Also written: of, oh.

Sources: English Wiktionary (homophones, alternative spellings).

What rhymes with o?

The 12 most written words on PlainSpell end in the same sounds as o from its last stressed vowel (/oʊ/):

Computed by PlainSpell from the pronunciations in the English Wiktionary (dump of September 2, 2026): a rhyme shares every sound from the last stressed vowel to the end; ordered by written frequency (wordfreq 3.1).

Forms of o

  • os plural
  • o's plural
  • oes plural
  • oh
  • more -o comparative
  • most -o superlative
  • a
  • õs plural
  • õ's plural

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).

What does o mean?

The meanings the English Wiktionary records, quoted as written there (source below).

letter

  1. 1

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

  2. 2

    Alternative form of ο, the fifteenth letter of the Classical and Modern Greek alphabets, called omicron and (astronomy) used as an abbreviation of omicron in star names.

    The system's Bayer designation is o Persei.

number

  1. 1

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

noun

  1. 1

    The name of the Latin script letter O/o.

  2. 2

    A zero (used in reading out numbers).

    It is currently two-o-five in the afternoon (2:05 PM).

  3. 3

    Operator

  4. 4

    Object, see SVO

letter

as O
  1. 1

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

noun

as O
  1. 1

    Something shaped like the letter O.

  2. 2

    A blood type that lacks A or B antigens and may only receive transfusions of similar type O blood, but may donate to all (neglecting Rh factor). Synonym: universal donor.

  3. 3

    An utterance of the vocative O.

  4. 4

    American Library Association abbreviation of octavo, a book size (20-25 cm).

  5. 5

    Someone associated with Leyton Orient Football Club, as a player, coach, supporter etc.

  6. 6

    The number of overs bowled.

  7. 7

    slangOrgasm.

  8. 8

    slangOpium.

number

as O
  1. 1

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

particle

as O
  1. 1

    The vocative particle, used for direct address.

    O Death! O Death! Won't you spare me over till another year? - part of the refrain from the American folk song "A Conversation with Death".

adjective

as O
  1. 1

    Abbreviation of morally offensive, film classification of the National Legion of Decency.

  2. 2

    Abbreviation of Orthodox.

  3. 3

    colloquialWith sugar and no condensed milk added.

symbol

as ō
  1. 1

    A dictionary transcription for the GOAT vowel

letter

as õ
  1. 1

    obsoleteThe letter o with a tilde, replacing the sequence on or om.

    cõpose – compose

symbol

as ô
  1. 1

    A dictionary transcription for the THOUGHT vowel; also an orthographic ⟨o⟩ with a diacritic that marks it as having that value, as in the word "nor".

symbol

as ö
  1. 1

    A dictionary transcription for the THOUGHT vowel

  2. 2

    – see ◌̈

symbol

as ȯ
  1. 1

    A dictionary transcription for the THOUGHT vowel

symbol

as ŏ
  1. 1

    A dictionary transcription for the LOT vowel

symbol

as o̱
  1. 1

    datedAn orthographic ⟨o⟩ with a diacritic that marks it as being the STRUT vowel, as in the word "son".

interjection

  1. 1

    Alternative form of oh.

adjective

  1. 1

    Clipping of over.

preposition

  1. 1

    Alternative form of of.

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).

O in Spanish, French, German and Portuguese

LanguageWords
Frencho (name of the letter O, o), ô (a vocative particle)
Portugueseó, ô (name of the letter O, o), -o-, -ó-, -ô- (linking vowel between morphemes)
Spanisho (name of the letter O, o), oh, oy (a vocative particle)
Germano (a vocative particle)

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Translations are Wiktionary's, by sense; a linked word has its own PlainSpell page.

What to look up after o