Ha

Ha may refer to:

Agencies and organizations

 * Health authority
 * Hells Angels Motorcycle Club
 * Highways Agency (renamed Highways England, now National Highways), UK government body maintaining England's major roads
 * Homelessness Australia, peak body organisation for homeless people and services
 * Homosexuals Anonymous an ex-gay program for dealing with unwanted same-sex attractions
 * Hong Kong Housing Authority

Arts, entertainment, and media

 * Ha (Doseone album), 2005
 * Ha (Talvin Singh album), 2002
 * Ha! (Killing Joke album), 1982
 * "Ha" (song), by Juvenile
 * Ha! (TV channel), an American all-comedy TV channel
 * Hamar Arbeiderblad, a Norwegian newspaper
 * Human Action, a book by the Austrian economist Ludwig von Mises
 * The Jim Henson Company, formerly known as ha!

Language

 * Ha (Javanese) (ꦲ), a letter in the Javanese script
 * Ha (kana), in syllabic Japanese script
 * ه (hāʾ), ح (ḥāʾ), or خ (ḫāʾ), Arabic letters
 * Ha language, the language of the Ha people in eastern Africa
 * Hausa language, ISO 639-1 code HA

Places

 * Ha, Bhutan
 * Hå, Norway
 * Ha Gorge, Greece
 * HA postcode area, a group of English postal districts in north-west London
 * Henan, a province of China (Guobiao abbreviation HA)

Chemistry

 * Hahnium, an element now called Dubnium
 * Hyaluronan (Hyaluronic acid), a carbohydrate structure
 * Hydroxylapatite, a mineral

Medicine

 * Hyperandrogenic anovulation, also called polycystic ovary syndrome
 * Health anxiety (HA) or hypochondriasis (hypochondria)
 * Hemagglutinin (influenza) (HA), an antigenic glycoprotein from Influenza viruses
 * Hemagglutination assay, a measurement of viruses or bacteria

Units of measure

 * Hartree, an atomic unit of energy
 * Hectare (ha), a unit of area
 * Hectoampere, a unit of electric current

Other uses in science and technology

 * ha (function prefix) (half), a prefix for some trigonometric functions in mathematics
 * High availability, systems design and implementation with a view to maximising service
 * Hour angle, in astronomy, one of the coordinates of the equatorial coordinate system
 * Ha, or alternative hypothesis, in statistical testing
 * H-alpha (Hα), a deep-red visible spectral line of the hydrogen atom

Surnames

 * Ha (Chinese surname) (哈), found in the Hundred Family Surnames
 * Ha (Korean surname) (하, 河 or 夏)
 * Hà, Vietnamese surname
 * Xia (surname) (夏), romanized as Ha in Cantonese, Korean and Vietnamese pronunciation

Transportation

 * British Rail Class 71, a locomotive (classified type HA under the Southern Region's pre-TOPS scheme)
 * Hawaiian Airlines (IATA designator HA)
 * Highways Agency (now National Highways), UK government body maintaining England's major roads

Other uses

 * Ha (mythology)
 * Ha, one of deities Heng and Ha
 * Ha people, a Tanzanian people
 * Hospitalman Apprentice, a U.S. Navy rank