DD, dd, or other variants may refer to:

  • DD in hexadecimal = 221
  • DD, a brassiere measurement
  • d.d., Croatian term for a public limited liability company; dioničko društvo (literal: joint stock company)
  • DD National or DD1, an Indian national channel
  • DuPont's stock ticker symbol
  • .dd, a hypothetical domain name for the German Democratic Republic
  • dd, an HTML element for specifying definition data
  • dd (Unix), a program that copies and convert files and data
  • Deckadance, a DJ program for Windows and Mac OS X designed by Image-Line
  • Deployment descriptor, a component in Java Platform, Enterprise Edition applications
  • Logo for Dolby Digital, audio compression technologies developed by Dolby Laboratories
  • Double density, a capacity designation on magnetic storage, usually floppy disks
  • Daredevil, a Marvel Comics character
  • DD, a character in The Saga of Seven Suns novels by Kevin J. Anderson.
  • DD tank, an amphibious tank
  • Dishonorable discharge, a punitive discharge in the US Military
  • DD, the US Navy hull classification for destroyers
Science and technology
  • Data Deficient, a rating on the IUCN Red List of Threatened Species
  • Decimal degrees, geographic coordinates shown using decimal fractions
  • D-D locomotive, the AAR classification for a railway locomotive with two four-axle bogies
  • Nok Air's IATA code
  • DD, the licence plate code for Dresden, Germany
Other uses
  • Dd (digraph), a digraph in the Welsh language
  • Degree of Difficulty, a diving score modifier
  • Doctor of Divinity or D.D.
  • Direct deposit, used in banking
  • Drug and Disease, used in Personals ads as "D&D Free"