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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

When DI Glyn Walsh returns unexpectedly early from bereavement leave, he and DS Sion Dearden work together to solve the perplexing murder of an esteemed university professor.

From BBC • Apr. 3, 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

The DI Council also moved forward on legislation that would allow schools to be more actively involved in securing sponsorship deals for their athletes.

From Seattle Times • Apr. 17, 2024

Since then CI is the refraction of the radius BC, and DI is parallel to CM, VC must be to CD as N to GC, according to what has been demonstrated in Article 31.

From Treatise on Light by Huygens, Christiaan