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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.

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di ² American  

[dee] / di /

noun

Music.

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

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Di ³ American  

[dahy] / daɪ /

noun

1. a female given name, form of Diana.

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Di ⁴ American  

Symbol, Chemistry.

1. didymium.

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DI ⁵ American  

1. Department of the Interior.

2. drill instructor.

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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 ).

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di- ⁷ American  

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

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di- ⁸ American  

1. variant of dia- before a vowel.

   diorama.

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di. ⁹ American  

Or dia

abbreviation

1. diameter.

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di- ¹ British  

combining form

1. variant of dia-

   diopter

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Di ² British  

symbol

1. didymium

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di- ³ British  

prefix

1. twice; two; double

   dicotyledon

2. 1. containing two specified atoms or groups of atoms

      dimethyl ether

      carbon dioxide

   2. a nontechnical equivalent of bi- 1

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DI ⁴ British  

abbreviation

1. Defence Intelligence

2. Detective Inspector

3. Donor Insemination

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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.

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Etymology

Origin of di¹

< Italian < Latin dē

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

“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

Ann Cleeves reportedly ended the Shetland mysteries with 2018’s “Wild Fire,” although Detective Inspector Jimmy Perez’s colleagues, led by DI Ruth Calder, continue in the TV series.

From Los Angeles Times • Sep. 29, 2025

DI Rob Smith, from the Major Crime Investigation Team, thanked the public for their support during the initial investigation.

From BBC • May 31, 2025

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

From Seattle Times • Apr. 17, 2024

And because DI is parallel to CM, the conjugate diameter to CG, it follows that KI touches the Ellipse at I; which remained to be shown.

From Treatise on Light by Huygens, Christiaan