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  • di
    di
    preposition
    from; of: used in Italian personal names, originally to indicate place of origin.
  • Di
    Di
    noun
    a female given name, form of Diana.
  • DI
    DI
    Department of the Interior.
  • di-
    di-
    a prefix occurring in loanwords from Greek, where it meant “two,” “twice,” “double” (diphthong ); on this model, freely used in the formation of compound words (dicotyledon; dipolar ) and in chemical terms (diatomic; disulfide ).
  • di.
    di.
    abbreviation
    diameter.
  • di–
    di–
    A prefix that means “two,” “twice,” or “double.” It is used commonly in chemistry, as in dioxide, a compound having two oxygen atoms.

di

1 American  
[dee] / di /
Or Di

preposition

  1. from; of: used in Italian personal names, originally to indicate place of origin.

    Conte di Savòia.


di 2 American  
[dee] / di /

noun

Music.
  1. a tone in the ascending chromatic scale between do and re.


Di 3 American  
[dahy] / daɪ /

noun

  1. a female given name, form of Diana.


Di 4 American  
Symbol, Chemistry.
  1. didymium.


DI 5 American  
  1. Department of the Interior.

  2. drill instructor.


di- 6 American  
  1. a prefix occurring in loanwords from Greek, where it meant “two,” “twice,” “double” (diphthong ); on this model, freely used in the formation of compound words (dicotyledon; dipolar ) and in chemical terms (diatomic; disulfide ).


di- 7 American  
  1. variant of dis- before b, d, l, m, n, r, s, v, and sometimes g and j: digest; divide.


di- 8 American  
  1. variant of dia- before a vowel.

    diorama.


di. 9 American  
Or dia

abbreviation

  1. diameter.


di- 1 British  

combining form

  1. variant of dia-

    diopter

"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

Di 2 British  

symbol

  1. didymium

"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

di- 3 British  

prefix

  1. twice; two; double

    dicotyledon

    1. containing two specified atoms or groups of atoms

      dimethyl ether

      carbon dioxide

    2. a nontechnical equivalent of bi- 1

"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

DI 4 British  

abbreviation

  1. Defence Intelligence

  2. Detective Inspector

  3. Donor Insemination

"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

di– Scientific  
  1. A prefix that means “two,” “twice,” or “double.” It is used commonly in chemistry, as in dioxide, a compound having two oxygen atoms.


Etymology

Origin of di1

< Italian < Latin

Origin of di2

Perhaps alteration of do 2

Origin of di-6

Middle English ≪ Latin < Greek, combining form representing dís twice, double, akin to dýo two. See bi- 1, twi-

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

The new findings, published in the Journal of Geophysical Research -- Solid Earth, were developed in collaboration with Anna Rosa Corsaro of the Istituto Nazionale di Geofisica e Vulcanologia in Catania.

From Science Daily Jul. 10, 2026

Still, Luca di Montezemolo, Ferrari’s former chairman, told reporters on Tuesday that the automaker is “risking the destruction of a legend.”

From Los Angeles Times May 27, 2026

“If I say what I think, I’d cause harm to Ferrari. We’re risking the destruction of an icon,” former Chairman Luca di Montezemolo said to local media.

From The Wall Street Journal May 26, 2026

He has also worked as music director of the Orchestre de Paris, the Accademia Nazionale di Santa Cecilia in Rome, and the Swedish Radio Symphony Orchestra.

From BBC May 26, 2026

He had a hard time imagining Nico di Angelo acting out of love for anybody, except maybe Hazel.

From "The House of Hades" by Rick Riordan

XS.com’s Antonio Di Giacomo expects gold prices to increase gradually from a technical perspective, as long as it maintains above $4,000 a troy ounce, with $4,100 as the immediate resistance level.

From The Wall Street Journal Jul. 22, 2026

"We're not in a drought situation yet, but at this rate, there's less than three weeks of water left in reserve," said Damiano Di Simine, an expert with environmental group Legambiente.

From Barron's Jun. 27, 2026

Di Dio went missing in June 1995 when she was 37.

From BBC Jun. 16, 2026

"The mouse models gave us a biological 'Rosetta Stone,'" said Dr. Adriana Di Martino at the Child Mind Institute.

From Science Daily Jun. 3, 2026

“He’s done magic for heads of state,” in addition to Muhammad Ali and Princess Di.

From "A Deadly Wandering: A Mystery, a Landmark Investigation, and the Astonishing Science of Attention in the Digital Age" by Matt Richtel

DI Collins appealed for anyone with information to contact the police.

From BBC Jun. 19, 2026

“We think the DI progress in particular could see consensus expectations for full year margins increase towards the upper half of the guided range, driving a positive reaction to the shares today,” Citi analysts wrote.

From The Wall Street Journal Feb. 12, 2026

JD Wyatt gives Poly 47-37 lead after three quarters of DI semifinal at Granada Hills.

From Los Angeles Times Feb. 27, 2025

It still needs to be ratified by the DI Board next week, but that is expected.

From Seattle Times Apr. 17, 2024

With regard to their names, all four of them come from the same Aryan root DI, meaning “bright,” which occurs in the names of the corresponding Greek deities, Zeus and his old female consort Dione.

From The Golden Bough by Frazer, James George, Sir

"This relationship aligns with natural shifts in the color of ambient illumination, detectable during twilight by mammals with di- and tri-chromatic visual systems."

From Salon Nov. 8, 2023

What about lecithin and mono-, di-, and triglycerides?

From "The Omnivore's Dilemma" by Michael Pollan

In the midafternoon, when the sun is high overhead—the earth’s equator close to the ball of burning fire, just like the di- agram in Understanding Our Universe—we turn onto the dirt road to Yana Urku.

From "The Queen of Water" by Laura Resau

NOTE.—The forms di- and dif- are euphonic forms of dis-; dif- is used before a root beginning with a vowel.

From New Word-Analysis by William Swinton

Nitro-benzene, di-nitrobenzene, and mono-, di-, and tri-nitro-naphthalenes behave similarly.

From Nitro-Explosives: A Practical Treatise by Sanford, P. Gerald (Percy Gerald)

Thomy ten. di. feod. in Bliston dict. feod.

From The Survey of Cornwall And an epistle concerning the excellencies of the English tongue by Carew, Richard

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