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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

duos plural

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

Rice has emerged as a star this season, partnering with Aaron Judge to form the most dangerous power duo in baseball.

From The Wall Street Journal • May 21, 2026

Nico O'Reilly's outstanding form for Manchester City means he will almost certainly be selected, with Newcastle duo Dan Burn and Lewis Hall also hoping to get the nod.

From BBC • May 21, 2026

The duo stayed in touch, with Gatto still a member of 2dust.

From Los Angeles Times • May 21, 2026

They fended off competition from fellow finalists, sibling side Harrison and Katie from Manchester, daughter-and-dad duo Molly and Andrew from Maghera, Northern Ireland, and English in-laws Mark and Margo.

From BBC • May 21, 2026

Together, the vengeful young duo fights to stamp out Nazi aggression in the Soviet Union.

From "A Thousand Sisters" by Elizabeth Wein

Related Words

• pair