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• duo
  duo

  noun

  duet.
• duo-
  duo-

  a combining form meaning “two,” used in the formation of compound words.

duo

¹ American  

[doo-oh, dyoo-oh] / ˈdu oʊ, ˈdyu oʊ /

noun

plural

duos

1. Music. duet.

2. two persons commonly associated with each other; couple.

3. two animals or objects of the same sort; two things ordinarily placed or found together; a pair.

   a duo of lovebirds.

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duo- ² American  

1. a combining form meaning “two,” used in the formation of compound words.

   duologue.

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duo ¹ British  

/ ˈdjuːəʊ /

noun

1. music

   1. a pair of performers

   2. another word for duet

2. a pair of actors, entertainers, etc

3. informal a pair of closely connected individuals

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duo- ² British  

combining form

1. indicating two

   duotone

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Usage

What does duo- mean? Duo- is a combining form used like a prefix meaning “two.” It is occasionally used in technical terms. Duo- comes from Greek dýo and Latin duo, both meaning “two.” In fact, English’s own word two is related to these roots! Learn more at our entry at two.

Etymology

Origin of duo¹

1580–90; < Italian < Latin: two

Origin of duo-²

Combining form of Greek dýo, Latin duo two

Compare meaning

How does duo compare to similar and commonly confused words? Explore the most common comparisons:

• duo vs. duet

Explanation

A duo is a pair of things or people. Batman and Robin are a famous dynamic duo, but a duo is any two people doing something together, not just crime fighting. In fact, a duo usually entertains. You can complain that you can't find a duo of matching socks, but it's more common to use duo for people who perform together. For example, Penn and Teller are a magician duo, and Laurel and Hardy were a comedy duo. If you and your sister play your ukuleles together in the subway for tips, you're also a duo. Originally, a duo was a song written for two voices, from the Latin meaning of duo, "two."

Example Sentences

Investors worry AI-driven code generation is hindering GitLab’s growth, with its Duo Agent Platform not expected to boost revenue this year.

From Barron's • Mar. 4, 2026

The “Amen” singer also acknowledged that winning his Grammy on “the first day of Black History Month and becoming the first Black man to win Best Country Duo is Black history.”

From Los Angeles Times • Feb. 4, 2026

Finally, by cross-referencing my room type and date of stay, she identified my holy grail as the Hotel Bellazure Duo Down Soft Feather Pillow, which I promptly ordered online for $95.

From The Wall Street Journal • Nov. 1, 2025

The individual plan is rising by $1, the Duo plan by $2, and the family subscription by $3.

From Slate • Jun. 5, 2024

The spirit and form of my Duo Concertant were determined by my love of the pastoral poets of antiquity and their scholarly art and technique.

From An Autobiography by Stravinsky, Igor

Related Words

• pair