oo
"oo" is a 2-letter English headword indexed on PlainSpell.
The verdict
“oo” is a moderately-common English word, ranked #13,572 in English word frequency and used as a noun.
- #13,572
- frequency rank, English
- 2
- letters
- 20
- confusable pairs
According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - (Ω, ω) The Greek letter omega.
Visual similarity to commonly confused words
How many letter changes separate each confused pair (Levenshtein distance, normalized).
Source: PlainSpell confusable corpus (Wiktionary, CC BY-SA).
| Property | Value |
|---|---|
| Headword | oo |
| Language | English |
| Part of speech | Noun |
| Letters | 2 |
| Frequency rank | #13,572 |
| Misspellings tracked | 0 |
| Confusable pairs | 20 |
| Source | Wiktionary (kaikki.org) |
Where “oo” sits in English frequency
Spelling & Dictionary Insight
The English entry for oo is 2 letters long, classified as a noun. Corpus data places it at rank #13,572 in overall English word frequency, marking it as uncommon enough that many writers pause before typing it. The dominant gloss from Wiktionary reads: "(Ω, ω) The Greek letter omega.".
oo has no tracked misspelling variants, which points to an orthography that plays by predictable English rules. It also participates in 20 confusable-pair relationships, "or", "op", "OS", and more, where similar look or sound leads writers to substitute one word for another in context.
Etymologically, the entry records: Representation of a long-o sound. The correct English form is oo, spelled O-O.
Definition
- 1(Ω, ω) The Greek letter omega.
Etymology
Representation of a long-o sound.
Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.
Frequently Asked Questions
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Using “oo”
The practical upshot for anyone who landed here from a spell-check.
- The one correct English spelling is O-O - every other letter order is a misspelling in standard orthography.
- Don't mix it up with “or” - see the side-by-side comparison. oo vs or
- Browse more English words and confusable pairs in the same reference. English words
Data Source
Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.