big O

English

Pronunciation

• Audio (General Australian):

  (file)

Noun

big O (plural big Os)

1. (mathematical analysis) Upper bound function; see big O notation.
2. (slang, usually preceded by "the") Orgasm.
   • 2024 August 26, Kimberly Delarosa, “Can Orgasms Make You Smarter? Here’s What Experts Say”, in Glamour‎:

     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%”, Bookfox

     Think of the faked O in Harry Met Sally, what she did in that restaurant.

3. (slang) Opium.

   Synonyms: see Thesaurus:opium

Further reading

• “big O n.”, in Green’s Dictionary of Slang, Jonathon Green, 2016–present
• Eric Partridge (2005), “Big O”, in Tom Dalzell and Terry Victor, editors, The New Partridge Dictionary of Slang and Unconventional English, volume 1 (A–I), London; New York, N.Y.: Routledge, →ISBN, page 151.

Anagrams

• Gobi, Igbo, biog, biog., gobi