H.D. (born Hilda Doolittle; September 10, 1886 – September 27, 1961) was an American poet, novelist and memoirist known for her association with the early 20th century avant-garde Imagist group of poets such as Ezra Pound and Richard Aldington. The Imagist model was based on the idioms, rhythms and clarity of common speech, and freedom to choose subject matter as the writer saw fit. H.D.'s later writing developed on this aesthetic to incorporate a more gynocentric version of modernism.

HD may refer to:

• High-definition, reference to:
  • high-definition video
  • high-definition television (HDTV)
  • Intel High Definition Audio
  • HD Voice
• Hard disk, a computer device which stores digitally encoded data, also known as 'hard drive' or 'hard disk drive' (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
• 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

Harley-Davidson Inc (

1. redirect, formerly HDI), often abbreviated H-D or Harley, is an American motorcycle manufacturer. Founded in Milwaukee, Wisconsin, during the first decade of the 20th century, it was one of two major American motorcycle manufacturers to survive the Great Depression. Harley-Davidson also survived a period of poor quality control and competition from Japanese manufacturers.