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a combining form meaning “double,” “in pairs,” used in the formation of compound words: diplococcus.
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Also especially before a vowel, dipl-.

Origin of diplo-

<Greek, combining form of diplóostwofold
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022


What does diplo- mean?

Diplo- is a combining form used like a prefix meaning “double” or “in pairs.” This form is frequently used in scientific terms, especially in zoology and botany.

Diplo- comes from Greek diplóos, meaning “twofold” or “double-folded.” Distantly related is Latin duplex, which also literally means “twofold.”

What are variants of diplo-?

When combined with words or word elements that begin with a vowel, diplo- becomes dipl-, as in diploid.

Examples of diplo-

One example of a term that features diplo- you may have seen is diplodocus, “a huge herbivorous dinosaur of the genus Diplodocus, growing to a length of about 87 feet.” Diplodocus comes from the New Latin Diplodocus, which uses the equivalent of the form diplo-.

As we know, diplo- means “double,” while the -docus part of diplodocus means “beam, bar, shaft,” from Greek dokós. Diplodocus literally translates to “double beams,” a reference to the double row of bones in its tail.

What are some words that use the combining form diplo- or dipl-?

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

Not every word that begins with the letters diplo- is necessarily using the combining form diplo- to mean “double.” Diploma and diplomatic are two such examples. Both of these words, as it happens, ultimately come from the same root as diplo-, but they aren’t using diplo- as a combining form. Learn why diploma is a type of document and why diplomatic means “tactful” at our entry for each word.

Break it down!

In suffix -oid means “resembling, like.” With this in mind, what does diploid mean?

How to use diplo- in a sentence

British Dictionary definitions for diplo-


before a vowel dipl-

combining form

Word Origin for diplo-

from Greek, from diploos, from di- 1 + -ploos -fold
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012