SINCE 1828
dictionary
thesaurus

double-o

noun, often capitalized O
Save Word
plural -s

Definition of double-o

: a close examination or inspection gave the two strangers the well-known double-o— Walker Matheson

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

  • More than 250,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

History and Etymology for double-o

so called from the two O's in once-over

Learn More About double-o

Dictionary Entries Near double-o

double numeration

double-o

double occupancy

See More Nearby Entries 

Statistics for double-o

Cite this Entry

“Double-o.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/double-o. Accessed 25 Jun. 2022.

Style: MLA
MLACheck Mark Icon ChicagoCheck Mark Icon APACheck Mark Icon Merriam-WebsterCheck Mark Icon

WORD OF THE DAY

noisome

Listen to the pronunciation of noisome

See Definitions and Examples »

Test Your Vocabulary

Name That Food

  • a-light
  • Name these cookies!
True or False

Test your knowledge - and maybe learn something along the way.

TAKE THE QUIZ
Universal Daily Crossword

A daily challenge for crossword fanatics.

TAKE THE QUIZ
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Words at Play
Ask the Editors
Word Games