HD

HD may refer to:

Science and technology

High-definition, reference to:
Hard drive, a computer device which stores digitally encoded data, also known as HDD
Henry Draper Catalogue, an astronomical catalogue often used to designate stars
High density, in reference to a floppy disk, other magnetic media or the optical formats HD DVD and Blu-ray Disc
Homeopathic doctor, a doctor whom practices homeopathy, also known as HD
Hybrid drive, a type of notebook computer hard drive that utilizes a large buffer
Hydrogen deuteride, a diatomic compound of hydrogen and deuterium
HD Radio, an abbreviation from the term Hybrid Digital/analog radio
HD Photo, an image format
The chemical warfare agent sulfur mustard, which in its distilled form is referred to as HD
Hyperdeformation, extremely deformed atomic nuclei
High-density polyethylene, a high-density polyethylene plastic material seen in milk containers and various juice beverages
Human Development

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

Harley-Davidson, an iconic American motorcycle manufacturer established in 1903
Headphone Dust, a record label run by music artist Steven Wilson
Hokkaido International Airlines, a Japanese low-cost airline with IATA designator HD established in 1996
The Home Depot, a chain of home improvement warehouse retailers established in 1978

Attention deficit hyperactivity disorder, known as Hyperactivity Disorder (HD), as in AD/HD
Hemodialysis, Renal dialysis
Hip dysplasia
Hirschsprung's disease
Hodgkin's disease, a blood Lymphoma cancers
Hormone disruptor
Huntington's disease, a genetic disorder affecting the central nervous system
The HD gene, a historical name for the huntingtin gene, which can cause Huntington's disease when it has certain properties
Hansen's disease (leprosy)

The HD postcode area, covering Huddersfield, Brighouse and Holmfirth in England, UK
Hunedoara (HD), an abbreviation for Hunedoara County, Romania, or code used on Romanian license plates for Hunedoara County
Heidelberg (code used on German license 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
Hawaiian Dick, a 2002 comicbook
H&D speed numbers, an old scale for measuring film speed established by Hurter & Driffield