| H | altitude |
| H | altitude rate |
| H | hazardous (task classification) |
| H | henry (SI unit) |
| H | momentum |
| H&D | hardened and dispersed |
| H&K | homing and kill |
| H-CITE | horizontal cargo integration test equipment |
| H-S | Hamilton Standard |
| H-S | horizon scanner |
| H-S | horizon sensor |
| H/A | hazardous area |
| H/B | hyperbaric |
| H/C | head count |
| H/E | heat exchanger |
| H/F | human factor |
| H/L | hardline |
| H/O | handover |
| H/S | heat shield |
| H/SIR | hardware and software integration review |
| H/X | heat exchanger |
| H2O2 | hydrogen peroxide |
| H2S | hydrogen sulfide |
| HA | apogee altitude |
| HA | hazard analysis |
| HA | high altitude |
| HA | higher authority |
| HAA | high-altitude abort |
| HAADS | high-altitude attitude determination system |
| HAARS | high-altitude attitude reference system |
| HAB | high-altitude burst |
| HABP | Hypersonic Arbitrary Body Program |
| HAC | Hughes Aircraft Company |
| HAC | heading alignment circle |
| HAC | heading alignment cylinder |
| HAD | heat-actuated device |
| HAFB | Hill Air Force Base |
| HAFB | Holloman Air Force Base |
| HAINS | high-accuracy inertial navigation system |
| HAK | horizontal access kit |
| HAL | Houston aerospace language |
| HAL | high-order articulated language |
| HAL | high-order assembly language |
| HAL/S | high-order assembly language for Shuttle |
| HAL/S | high-order programming language for Spacelab usage |
| HALO | high-altitude large optics |
| HAM | height adjustment maneuver |
| HAMP | handling and moving procedure |
| HANE | high-altitude nuclear explosion |
| HAP | Hardware Allocation Panel |
| HAP | Honeywell array processor |
| HAP | high-speed arithmetic processor |
| HAR | hazard analysis report |
| HAS | high-altitude sensor |
| HAS | hold-down alignment support |
| HAS | hydraulic actuation system |
| HASC | high-altitude surveillance concept |
| HAST | high-altitude supersonic target |
| HAW | Hawaii (STDN) |
| HB | half-breadth |
| HB | handbook |
| HB | high bay |
| HB | hyperbaric |
| HBBW | half-beam bandwidth |
| HBR | high bit rate |
| HBT | Heflex bioengineering test |
| HBW | hot bridge wire |
| HC | hand control |
| HC | head count |
| HC | high carbon |
| HC | hybrid computer |
| HCCB | Hardware Configuration Control Board |
| HCDB | historical cost data base |
| HCF | HIM configuration file |
| HCF | high-cycle fatigue |
| HCI | hardness-critical item |
| HCM | hard-copy module |
| HCMM | heat capacity mapping mission |
| HCP | hydraulic circulation pump |
| HCR | high cross range |
| HCRB | Hardware Configuration Review Board |
| HCS | high-carbon steel |
| HCSHT | high-carbon steel heat-treated |
| HCSL | Hybrid Computation and Simulation Laboratory |
| HCU | hydraulic charging unit |
| HCV | helium check valve |
| HCl | hydrogen chloride |
| HD | hand-drawn |
| HD | heavy duty |
| HD | highly desirable |
| HD | hold-down |
| HD | horizontal drain |
| HD | hydrogen drain |
| HDA | hardware disposition area |
| HDA | housekeeping data acquisition |
| HDC | Hasselblad data camera |
| HDDR | high-density digital recorder |
| HDI | Human Development Institute |
| HDP | hold-down post |
| HDR | high data rate |
| HDRA | high-data-rate assembly |
| HDRM | high-data-rate multiplexer |
| HDRR | high-data-rate recorder |
| HDRS | high-data-rate system |
| HDRSS | high-data-rate storage system |
| HDS | hardware description sheet |
| HDS | hydrogen disposal system |
| HDTV | high-definition television |
| HDX | half-duplex |
| HE | hardware evaluation |
| HE | hardware evaluator |
| HE | heat exchange |
| HE | heat exchanger |
| HE | high explosive |
| HE | high explosive on target |
| HE | high-energy astrophysics |
| HE | human engineering |
| HEAO | High-Energy Astronomy Observatory |
| HEAP | high-energy aimpoint |
| HEDI | high endoatmospheric defense interceptor |
| HEDS | high endo designation sensor |
| HEDSIM | high endo simulation |
| HEDSIM | high endoatmospheric defense system simulator |
| HEDSIM | high endoatmospheric event-based simulation |
| HEL | high-energy laser |
| HELCUSS | high-energy laser computerized unmanned space |
| HELF | high-energy laser fluence |
| HEM | hitchhike experiment module |
| HEMIL | hardware evaluator, man in loop |
| HEO | high Earth orbit |
| HEO | high-energy orbit |
| HEOO | Honeywell Electro-Optical Operations |
| HEOR | historical event operation record |
| HEOS | high endo designator sensor |
| HEPA | high-efficiency particle accumulator |
| HEPA | high-efficiency particle air |
| HER | HIM equipment rack |
| HERSCP | hazardous exposure reduction and safety criteria plan |
| HERT | Headquarters Emergency Relocation Team |
| HESS | high-energy squib simulator |
| HEXAD | developmental 6-axis IMU |
| HF | hard failure |
| HF | high frequency |
| HF | horizontal flight |
| HF | hot firing |
| HF | hydrogen fill |
| HF | hydrogen fluoride |
| HF/DF | hydrogen fluoride/deuterium fluoride |
| HFA | high-frequency accelerometer |
| HFC | heat flow and convection |
| HFC | hydraulic flight control |
| HFCL | Hydraulic Flight Control Laboratory |
| HFCT | hydraulic flight control test |
| HFCV | helium flow control valve |
| HFCW | hydrogen fluoride continuous wave |
| HFDP | human factors development plan |
| HFDS | hydrogen fluid distribution system |
| HFE | high-frequency executive |
| HFE | human factors engineering |
| HFMP | human factors management plan |
| HFMU | high-fidelity mockup |
| HFO | high-frequency oscillator |
| HFP | hardened focal plane |
| HFRA | high-frequency recovery antenna |
| HFRW | high-frequency resistance welding |
| HFS | high-fidelity simulator |
| HFS | horizontal flight simulator |
| HFS | hyperfine structure |
| HFT | horizontal flight test |
| HFTE | human factors test and engineering |
| HFTF | horizontal flight test facility |
| HFTS | horizontal flight test simulator |
| HFX | high-frequency transceiver |
| HG | high gain |
| HGA | high-gain antenna |
| HGAS | high-gain antenna system |
| HGDS | hazardous gas detection system |
| HGM | hot-gas manifold |
| HGS | hydrogen gas saver |
| HGV | hydrogen gas valve |
| HGVT | horizontal ground vibration test |
| HH | handhold |
| HHMU | hand-held maneuvering unit |
| HI | Honeywell, Incorporated |
| HIAD | Handbook of Information for Aircraft Designers |
| HIAD | High-Altitude Defense Program |
| HIBREL | high-brightness relay |
| HIC | hardware integration contractor |
| HICAMP | Highly Calibrated Airborne Measurements Program |
| HID | HIM interface distributor |
| HID | hardware interface device |
| HIGED | Handbook of Instructions for Ground Equipment Designers |
| HIL | hardware in loop |
| HIL | human in the loop |
| HILS | hardware-in-the-loop simulation |
| HIM | hardware interface module |
| HIP | hardware interface panel |
| HIP | hardware interface processor |
| HIP | hardware interface program |
| HIP | hot isostatic press |
| HIPO | hierarchical input-process output |
| HIPO | hierarchy plus input, process, and output |
| HITS | hierarchical integrated test simulator |
| HITS | high-rate multiplexer input and output test system |
| HIU | headset interface unit |
| HIV | helium isolation valve |
| HK | housekeeping |
| HKV | hit-to-kill vehicle |
| HL | hard line |
| HL | heel line |
| HL | high level |
| HL | hinge line |
| HL | hydrogen line |
| HLAL | high-level assembler language |
| HLC | hybrid load controller |
| HLCM | high-level control module |
| HLLV | heavy-lift launch vehicle |
| HLTL | high-level test language |
| HM | hinge mount |
| HMA | hypergolic maintenance area |
| HMB | hard mobile basing |
| HMC | hybrid microcircuit |
| HMCF | hypergolic maintenance and checkout facility |
| HMD | head-mounted device |
| HMD | helmet-mounted display |
| HMF | health maintenance facility |
| HMF | horizontal mating facility |
| HMF | hypergolic maintenance facility (KSC) |
| HML | hard mobile launcher |
| HML | hardened mobile launcher |
| HMO | health maintenance organization |
| HMP | hydrazine monopropellant (RCS propellant) |
| HMPAC | helmet-mounted multipurpose applications control |
| HMS | hazard monitor system |
| HMS | health monitoring system |
| HMS | history memory system |
| HMTT | Hurricane Mesa Test Track |
| HMU | hardware mockup |
| HMV | hydrogen manual valve |
| HNCO | high-precision numerical-controlled oscillator |
| HO | hydrogen-oxygen |
| HOE | homing optical experiment |
| HOE | homing overlay experiment |
| HOFCO | horizontal functional checkout |
| HOL | high-order language |
| HOL | higher order language |
| HOLAB | holographic laboratory brassboard |
| HOLC | high-order language computer |
| HOS | high-order software |
| HOS | hybrid operating system |
| HOSC | Huntsville Operations Support Center |
| HOST | hardened optical sensor test bed |
| HOW | handover word |
| HP | Hewlett-Packard |
| HP | handling procedure |
| HP | high pass |
| HP | high pressure |
| HP | horsepower |
| HP | hydrogen purge |
| HP | perigee altitude |
| HP | pressure altitude |
| HPA | handling and positioning aid |
| HPA | high-power amplifier |
| HPA | high-power antenna |
| HPAU | high-power amplifier unit |
| HPBRM | high payload baseline reference mission |
| HPBW | half-power beam width |
| HPC | corrected pressure altitude |
| HPF | Horizontal Processing Facility |
| HPF | highest probable frequency |
| HPFT | high-pressure fuel turbopump |
| HPFTP | high-pressure fuel turbopump |
| HPG | high-pressure gas |
| HPGS | high-pressure gas system |
| HPI | high-performance insulation |
| HPICS | heat pipe instrumentation and control system |
| HPM | Harvard Project Manager |
| HPM | high-performance motor |
| HPM | high-power microwave |
| HPOL | High-Power Optics Laboratory |
| HPOP | high-pressure oxidizer pump |
| HPOT | high-pressure oxidizer turbopump |
| HPOTP | high-pressure oxidizer turbopump |
| HPPF | Horizontal Payloads Processing Facility |
| HPR | hydrogen pressure regulator |
| HPRV | hydrogen pressure relief valve |
| HPS | hydraulic power system |
| HPT | high-pressure test |
| HPU | high-power unit |
| HPU | hydraulic power unit |
| HPU | hydraulic propulsion unit |
| HPU | uncorrected pressure altitude |
| HPV | high-pressure valve |
| HQ | headquarters |
| HQR | handling qualities rating (Cooper-Harper) |
| HR | heat-resistant |
| HR | historical record |
| HR | hydrogen relief |
| HR&T | heat rejection and transport |
| HRAA | high-rate acquisition assembly |
| HRC | Hasselblad reflex camera |
| HRD | high-rate dosimeter |
| HRDA | high-rate data assembly |
| HRDM | high-rate demultiplexer |
| HRDR | high-rate digital recorder |
| HRE | hardware reuse evaluation |
| HRG | hemispherical resonating gyro |
| HRIR | high-resolution infrared radiometer |
| HRL | horizontal reference line |
| HRM | hand-held radiation meter |
| HRM | high-rate multiplexer |
| HRMA | high-resolution mirror assembly |
| HRPS | hazard reduction precedence sequence |
| HRSI | high-temperature reusable surface insulation |
| HRSO | high-resolution solar observatory |
| HRTS | HR&T system |
| HS | hard silo |
| HS | heat shield |
| HS | heat suppression |
| HS | high speed |
| HS | horizon sensor |
| HS | hot short |
| HS | hydrogen sulfide |
| HSA | heat shield abort |
| HSB | heat shield boost |
| HSC | hardware and software coordination |
| HSC | hierarchical storage controller |
| HSC | house spacecraft |
| HSCS | high-speed communications subsystem |
| HSCU | hydraulic supply and checkout unit |
| HSD | Hamilton Standard Division |
| HSD | high-speed data |
| HSD | high-speed device |
| HSD | horizontal situation display |
| HSDL | high-speed data line |
| HSE | heat shield entry |
| HSF | Hypergolic Servicing Facility |
| HSG | high sustained g's (acceleration) |
| HSG | high-speed gear |
| HSI | horizontal situation indicator |
| HSIG | hermetically sealed integrating gyroscope |
| HSK | horizontal sling kit |
| HSL | Hardware Simulation Laboratory |
| HSP | high-speed printer |
| HSR | hardware status register |
| HSR | heat-shield recovery |
| HSR | high speed reader |
| HSRV | heat-source reentry vehicle |
| HSS | high stress/strain |
| HSSM | hardened space sensor model |
| HST | Hubble Space Telescope |
| HSTF | Hypergolic System Test Facility |
| HSU | helium service unit |
| HSV | hypersonic vehicle |
| HT | Hadamard transform |
| HT | heat transfer |
| HT | heat treatment |
| HT | heat-treat |
| HT | high technology |
| HTC | high-temperature carbon |
| HTC | hybrid technology computer |
| HTE | hazardous top-level event |
| HTLL | high-test-level language |
| HTM | high-throughput mission |
| HTO | horizontal takeoff |
| HTP | hydroxyl terminated propellant |
| HTPB | hydroxyl terminated polybutylene |
| HTPB | hydroxyl terminator polybutadiene |
| HTS | Hawaii tracking station |
| HTS | heat transfer system |
| HTS | heat transport section |
| HUD | head-up display |
| HUL | hardware utilization list |
| HULL | hardware utilization and location list |
| HUT | hard upper torso |
| HV | high velocity |
| HV | high voltage |
| HV | hydrogen vent |
| HVAC | heating, ventilation, and air conditioning |
| HVDS | hazardous vapor detection system |
| HVE | high-voltage electronics |
| HVI | high-velocity impact |
| HVM | hydraulic valve module |
| HVM | hypervelocity missile |
| HVPS | high-voltage power supply |
| HVSF | Honeywell Verification Simulation Facility |
| HVSL | holidays, vacation, and sick leave |
| HW | half word |
| HW | hardware |
| HW | head wind |
| HW | heavyweight |
| HW | hot wire |
| HW/SW | hardware/software |
| HWCI | hardware configuration item |
| HWIL | hardware in loop |
| HWT | hypersonic wind tunnel |
| HX | heat exchanger |
| HYDAC | hybrid digital-analog computer |
| HYPACE | hybrid programmable attitude control electronics |
| HYSAT | hybrid satellite |
| HYSAT | hybrid sensor experimental satellite |
| HeG | helium gauge |
| HeGV | helium gauge valve |
| HeMV | helium manual valve |
| HgCdTe | mercury-cadmium-telluride |
| HiRAP | high-resolution accelerometer package |
| Hz | hertz (cycles per second) |