big O
"big-o" is a 4-letter English headword indexed on PlainSpell.
The verdict
“big O” is uncommon English (outside the top frequency list), classed as a noun. The kind of spelling people second-guess.
- Unranked
- below top-frequency English
- 5
- letters
According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Upper bound function; see big O notation.
Corpus desk
Index EN-big-o · big O · English
big O · unranked · 0 variants · 0 confusables
- FREQ-UNRANKED Unranked
- LEN-MID 5 letters
- VOW-2 2 vowels
- CONFUS-0 No pairs
- VAR-0 0 variants
- BOOK-THIN "B" thin
- PHOTO-UNK Peer pending
Read with this headword: Spelling guide for this pattern
Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.
| Property | Value |
|---|---|
| Headword | big O |
| Language | English |
| Part of speech | Noun |
| Letters | 5 |
| Misspellings tracked | 0 |
| Confusable pairs | 0 |
| Source | Wiktionary (kaikki.org) |
Long-tail rank of “big O” in English
Rare enough to double-check
big O is uncommon English outside the top frequency list, classed as anoun. Rarity is why readers land here mid-draft. 3 senses are on record.
No generated misspelling entries exist for big O in our index, which points to an orthography that plays by predictable English rules. We don't track a confusable pairing for this entry, which tends to mean the word is visually distinctive enough to stand on its own.
This entry carries no recorded etymology, so its spelling is easiest explained by how it's pronounced rather than where it came from. The correct English form is big O, spelled B-I-G- -O.
Definition
- 1Upper bound function; see big O notation.
- 2Orgasm.
- 3Opium.
Recorded use
Wiktionary examplesThese source excerpts show how big O appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.
Various sections of the brain are activated during the Big O, including the limbic system.
2025 October 21, John Matthew Fox, “9 Writing Strategies of Authors in the Top 1%”https://youtu.be/_EeaAfAOxTw?t=284s, Bookfox Think of the faked O in Harry Met Sally, what she did in that restaurant.
Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA). See the methodology for how each field is sourced and updated.