duo

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.

One example of a technical term that features the combining form duo- is duotone, “of two tones or colors.”

The combining form duo- means “two,” while -tone here means “color.” Duotone literally translates to “two colors” or “two-colored.”

What are some words that use the combining form duo-?

• duobinary
• duopoly
• duotype
• duologue
• duopsony

What are some other forms that duo- may be commonly confused with?

• deoxy-
• di-
• dia-

The combining form duodeno- does not use duo- to mean “two.” Learn why duodeno- represents a part of the small intestine at our entry.

A monologue is the part of a drama in which a single speaker talks at length. With this in mind, what is a duologue, also known as a dialogue?