(Main list of acronyms) h – (s) Hecto H – (s) Henry – Hydrogen HA ha – (s) Hausa language (ISO 639-1 code) – Hectare HA – (s) Haiti (FIPS 10-4 country code) – (i) High Availability HAARP – (a) High Frequency Active Auroral Research Program HAART – (a) Highly Active Anti-Retroviral Therapy HAI – (i) Human Awareness Institute HAL – (i) Hardware Abstraction Layer HALO – (a) Habitation and Logistics Outpost (of the planned Lunar Gateway space station) High Altitude Low Opening (parachute jump) HALT (a) Highly Accelerated Life Test (a) Hungry Angry Lonely Tired HAMR – (a) Heat-assisted magnetic recording HANS – (a) Head And Neck Support (device used in many race cars) HARM – (a) High-speed Anti-Radiation Missile hat – (s) Haitian Creole language (ISO 639-2 code) HAT – (i/a) Highest Astronomical Tide (nautical charts) – (a) Hungarian Automated Telescope hau – (s) Hausa language (ISO 639-2 code) HAW – (i) Heavy Antitank Weapon HAWK – (a) Homing All the Way Killer (air defence system) HAZ – (i) Heat-Affected Zone HAZMAT – (p) Hazardous Materials HB HBCD – (p) HexaBromoCycloDodecane HBCI – (i) Home Banking Computer Interface HBCU – (i) Historically black colleges and universities (U.S.) HBO – (i) Home Box Office HBR – (i) Harvard Business Review HBT – (i) Heterojunction Bipolar Transistor HBV – (i) Hepatitis B Virus HC h.c. – (i) honoris causa (Latin, "for the sake of honour") HCCI – (i) Homogeneous Charge Compression Ignition HCF – (i) Highest Common Factor HCI – (i) Human–Computer Interaction/Interface HCPCS – (i) Health Care Procedure Coding System HCSC – (i) Higher Command and Staff Course HCT – (i) Higher Colleges of Technology, tertiary education institution in the United Arab Emirates (UAE) HD HD (i) Henry Draper (star catalogue) Hull-Down (armored vehicle target, as opposed to Fully Exposed) High Definition Huntington's Disease HDD (i) Hard Disk Drive High-Density Disk HDL – (i) High-Density Lipoprotein HDM – (i) Human Decision-Making HDMI – High-Definition Multimedia Interface HDR (i) Hard disk recorder Henningson, Durham & Richardson (founders of the engineering and construction firm now known by their initials) High dynamic range, a term used in both digital imaging and 3D rendering Hot Dry Rock (experimental geothermal technology) Human Development Report (UN publication) HDRA – (i) Henry Doubleday Research Association HDTV – (p) High-definition television HE he – (s) Hebrew language (ISO 639-1 code) He – (s) Helium HE – (a)