HD

HD may refer to:

Academia

Higher diploma, an academic award
National History Day, an American history competition, somewhat similar to Science Fair

Hansen's disease, an eponymous name for leprosy
Hemodialysis, a form of renal dialysis
High dependency unit of a hospital, usually located next to the intensive care ward
Hip dysplasia (disambiguation)
Hirschsprung's disease, a disorder of the abdomen
Hodgkin's disease, a form of lymphoma
Hormone disruptor
Huntington's disease, a genetic disorder affecting the central nervous system
- HD (gene), also called HTT or IT-15, which encodes huntingtin protein and causes Huntington's disease when abnormally expanded
Hyperactivity disorder, another name for attention deficit hyperactivity disorder (ADHD)

HDStarcraft, American electronic sports shoutcaster
H.D., the pen name of Hilda Doolittle (1886–1961), a 20th-century American poet and novelist

Hard disk, a computer device which stores digitally encoded data, also known as 'hard drive' or 'hard disk drive'
In BIOS setup, number of heads in cylinder-head-sector (CHS) hard disk drive access method
HD Photo, an image format
HD Radio, an abbreviation from the term hybrid digital/analog radio
Henry Draper Catalogue, an astronomical catalogue often used to designate stars
High-definition, reference to:
- High-definition television (HDTV), a resolution that is substantially higher than that of standard-definition television
- High-definition video, video of higher resolution and quality than standard-definition
- Intel High Definition Audio, a specification for the audio sub-system of personal computers
- HD Voice, or wideband audio
High density, in reference to a floppy disk, other magnetic media or the optical formats HD DVD and Blu-ray Disc
High-density polyethylene, a high-density polyethylene plastic material seen in milk containers and various juice beverages
Hybrid drive, a type of notebook computer hard drive that utilizes a large buffer
Hydrogen deuteride, a diatomic compound of hydrogen and deuterium
Hyperdeformation, extremely deformed atomic nuclei
The chemical warfare agent sulfur mustard, which in its distilled form is referred to as HD

Helsingborgs Dagblad, a Swedish newspaper
Hawaiian Dick, a 2002 comicbook
HD postcode area, covering Huddersfield, Brighouse and Holmfirth in England, UK
Heidelberg, code used on German vehicle registration plates
Hit Dice, a statistic related to hit points, indicating role-playing game characters' health or durability
Holocaust denial, consists of claims that the genocide of Jews during World War II did not happen
Humpty Dumpty, a nursery rhyme character
Hurter and Driffield (H&D), speed numbers, an old scale for measuring film speed
Hunedoara County, Romania