[ mon-oh ]
/ ˈmɒn oʊ /
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noun Informal.
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Origin of mono

By shortening

Other definitions for mono (2 of 3)

[ mon-oh ]
/ ˈmɒn oʊ /


Origin of mono

By shortening

Other definitions for mono (3 of 3)


a combining form meaning “alone,” “single,” “one” (monogamy); specialized in some scientific terms to denote a monomolecular thickness (monolayer) and adapted in chemistry to apply to compounds containing one atom of a particular element (monohydrate).
Also especially before a vowel, mon- .

Origin of mono-

From Greek, combining form of mónos “alone”
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


What does mono- mean?

Mono- is a combining form used like a prefix meaning “alone, singular, one.” It is used in a great many technical and scientific terms, including in chemistry, where it refers to compounds containing one atom of a particular element.

Mono- comes from the Greek mónos, meaning “alone.”

What are variants of mono-?

When combined with words or word elements that begin with a vowel, mono- becomes mon-, as in monacid.

Examples of mono-

An example of a word you may have encountered that features mono- is monolith, “an obelisk, column, large statue, etc., formed of a single block of stone.” The word comes from the Greek monólithos, which uses the equivalent of the form mono-.

We know mono- means “one,” so what about the -lith portion of the word? That’s right, -lith refers to “stone,” from the Greek líthos. Monolith literally translates to “single stone.”

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

The following words use the equivalent forms of mono- in Latin or Greek:

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

Not every word that begins with the exact letters mono- or mon- is necessarily using the combining form mono- to denote “one,” e.g., monitor and monumental. Learn more about the Latin root of these words at our entries for them.

Break it down!

The combining form -cracy means “rule by” or “government.” How many people or parties run a monocracy, also known as an autocracy?

How to use mono in a sentence

British Dictionary definitions for mono (1 of 2)

/ (ˈmɒnəʊ) /

short for monophonic
monophonic sound; monophony

British Dictionary definitions for mono (2 of 2)


before a vowel mon-

combining form
one; singlemonochrome; monorail
indicating that a chemical compound contains a single specified atom or groupmonoxide

Word Origin for mono-

from Greek monos
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

Scientific definitions for mono


A prefix that means “one, only, single,” as in monochromatic, having only one color. It is often found in chemical names where it means “containing just one” of the specified atom or group, as in carbon monoxide, which is carbon attached to a single oxygen atom.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.