| HAP | High-Speed Arithmetic Processor | In English | → Hardware → Mathematics |
| HarAC | Harvard College Observatory Announcement Card | In English | → Serial publications, periodicals → Astronomy |
| HarAR | Harvard College Observatory Annual Report | In English | → Serial publications, periodicals → Astronomy |
| HarCi | Harvard College Observatory Circular | In English | → Serial publications, periodicals → Astronomy |
| HarPa | Harvard College Observatory Papers | In English | → Serial publications, periodicals → Astronomy |
| HarRe | Harvard College Observatory Reprints | In English | → Serial publications, periodicals → Astronomy |
| HarZi | Harthaer Beobachtungs-Zirkular | In German | → Serial publications, periodicals → Astronomy |
| HBB | Horizons in Biochemistry and Biophysics | In English | → Serial publications, periodicals → Biochemistry, biophysics |
| hBGP | Human Biliary Glycoprotein | In German | → Biological sciences |
| HBGP | Honey Bee Genome Project (www.hgsc.bcm.tmc.edu/projects/honeybee/) = HBGP | Honigbienen-Genomprojekt | In German |
In English | → Genetics |
| HBGP | Honigbienen-Genomprojekt (www.hgsc.bcm.tmc.edu/projects/honeybee/) = (look above) |
In German | → Genetics |
| HBP | Handbook of Biological Physics | In English | → Serial publications, periodicals → Biochemistry, biophysics |
| hCEA | Human Carcinoembryonic Antigen | In English | → Biological sciences |
| HCFC | Hydrochlorofluorocarbone | In French | → Chemistry → Chemical technology |
| HCST | Haut Conseil de la Science et de la Technologie | In French | → Engineering, technology |
| HCT | Hot Cell Technology | In English | → Nuclear, atomic, and molecular physics → 54458 → Nuclear technology |
| HDA | Handbuch der Astrophysik | In German | → Serial publications, periodicals → Astronomy |
| HDAC | Histone deacetylase | In English | → Genetics → Enzymes |
| HDL | High Density Lipoprotein | In English | → Biochemistry, biophysics |
| HDP | Handbuch der Physik | In German | → Serial publications, periodicals → Physics |
| He | Héiliam = He | Helium | In English = He | Hélium | In French = He | Helium | In German = He | Гелій | In Belarusian = He | Хелий | In Bulgarian = He | Heli | In Catalan = He | Helijum | In Czech = He | Eliu | In Corsican = He | হিলিয়াম | In Bengali = He | Heliwm | In Welsh = He | Ήλιο | In Greek = He | Helio | In Spanish = He | Heliumo | In Esperanto = He | هيليوم | In Arabic = He | Heelium | In Estonian = He | هلیوم | In Persian = He | הליום | In Hebrew = He | હીલિયમ | In Gujarati = He | Eli | In Friulian = He | हीलियम | In Hindi = He | Elyòm | In Haitian Creole = He | Հելիում | In Armenian = He | Helín | In Icelandic = He | ヘリウム | In Japanese = He | ჰელიუმი | In Georgian = He | 헬륨 | In Korean = He | Hêlyûm | In Kurdish = He | Haumāmā | In Māori = He | Хелиум | In Macedonian = He | Eliyúmu | In Lingala = He | Éli | In Lombard = He | ഹീലിയം | In Malayalam = He | हेलियम | In Marathi = He | Хелијум | In Serbian = He | Гелий | In Russian = He | Heliu | In Romanian = He | Tōnatiuyoh | En Nahuatl = He | Ilyu | In Quechua = He | ஹீலியம் | In Tamil = He | Гелій | In Ukrainian = He | 氦 | In Chinese = He | Geliy | In Uzbek = He | ฮีเลียม | In Thai |
In Irish | → Chemistry |
| He | હીલિયમ = (look above) |
In Gujarati | → Chemistry |
| He | הליום = (look above) |
In Hebrew | → Chemistry |
| He | هلیوم = (look above) |
In Persian | → Chemistry |
| He | हीलियम = (look above) |
In Hindi | → Chemistry |
| He | Haumāmā = (look above) |
In Māori | → Chemistry |
| He | Elyòm = (look above) |
In Haitian Creole | → Chemistry |
| He | Eli = (look above) |
In Friulian | → Chemistry |
| He | Հելիում = (look above) |
In Armenian | → Chemistry |
| He | Helín = (look above) |
In Icelandic | → Chemistry |
| He | Hêlyûm = (look above) |
In Kurdish | → Chemistry |
| He | 헬륨 = (look above) |
In Korean | → Chemistry |
| He | ヘリウム = (look above) |
In Japanese | → Chemistry |
| He | Heelium = (look above) |
In Estonian | → Chemistry |
| He | Eliyúmu = (look above) |
In Lingala | → Chemistry |
| He | Heliu = (look above) |
In Romanian | → Chemistry |
| He | Tōnatiuyoh = (look above) |
En Nahuatl | → Chemistry |
| He | Ilyu = (look above) |
In Quechua | → Chemistry |
| He | ஹீலியம் = (look above) |
In Tamil | → Chemistry |
| He | Гелій = (look above) |
In Ukrainian | → Chemistry |
| He | 氦 = (look above) |
In Chinese | → Chemistry |
| He | ഹീലിയം = (look above) |
In Malayalam | → Chemistry |
| He | Geliy = (look above) |
In Uzbek | → Chemistry |
| He | ฮีเลียม = (look above) |
In Thai | → Chemistry |
| He | Хелијум = (look above) |
In Serbian | → Chemistry |
| He | Éli = (look above) |
In Lombard | → Chemistry |
| He | हेलियम = (look above) |
In Marathi | → Chemistry |
| He | Хелиум = (look above) |
In Macedonian | → Chemistry |
| He | Гелий = (look above) |
In Russian | → Chemistry |
| He | هيليوم = (look above) |
In Arabic | → Chemistry |
| He | ჰელიუმი = (look above) |
In Georgian | → Chemistry |
| He | Helium = (look above) |
In English | → Chemistry |
| He | Hélium = (look above) |
In French | → Chemistry |
| He | Helium = (look above) |
In German | → Chemistry |
| He | Гелій = (look above) |
In Belarusian | → Chemistry |
| He | Хелий = (look above) |
In Bulgarian | → Chemistry |
| He | Heli = (look above) |
In Catalan | → Chemistry |
| He | Helijum = (look above) |
In Czech | → Chemistry |
| He | Heliumo = (look above) |
In Esperanto | → Chemistry |
| He | Helio = (look above) |
In Spanish | → Chemistry |
| He | Ήλιο = (look above) |
In Greek | → Chemistry |
| He | Heliwm = (look above) |
In Welsh | → Chemistry |
| He | হিলিয়াম = (look above) |
In Bengali | → Chemistry |
| He | Eliu = (look above) |
In Corsican | → Chemistry |
| HEAD | High Energy Astrophysics Division | In English | → Astronomy |
| HEAO | High-Energy Astronomy Observatory | In English | → Observatories |
| HEAO | High Energy Astronomical Observatory | In English | → Observatories |
| HECh | High Energy Chemistry | In English | → Serial publications, periodicals → Chemistry |
| HEJ | Hungarian Electronic Journal of Sciences | In English | → Serial publications, periodicals |
| HEL | High-Energy Laser | In English | → Optics → Electromagnetism |
| HELCUSS | High-Energy Laser Computerized Unmanned Space | In English | → Optics |
| HELF | High-Energy Laser Fluence | In English | → Optics |
| HELM | Hypertextual Electronic Library of Mathematics | In English | → Libraries → Data → Mathematics |
| HelOB | Helwan Institute of Astronomy and Geophysics Bulletins | In English | → Serial publications, periodicals → Astronomy → Geophysics |
| HemD | Hemel en Dampkring | In Dutch | → Serial publications, periodicals → Astronomy |
| HEO | High Earth Orbit | In English | → Astronomy → Spaceflight engineering, astronautics |
| HEO | High-Energy Orbit | In English | → Astronomy → Spaceflight engineering, astronautics |
| HEPNP | High Energy Physics and Nuclear Physics | In English | → Serial publications, periodicals → Nuclear, atomic, and molecular physics |
| HER | Hydroxyethylrutoside | In English | → Biochemistry, biophysics |
| HER | Human Epidermal growth factor Receptor | In English | → Biochemistry, biophysics |
| HERV | Human Endogenous RetroVirus | In English | → Virology |
| HESS | Hydrology and Earth System Sciences | In English | → Serial publications, periodicals → Hydrology |
| HESS | High-Energy Squib Simulator | In English | → Computer simulation → Physics |
| HESSD | Hydrology and Earth System Sciences Discussions | In English | → Serial publications, periodicals → Hydrology |
| HEW | Hindu Kush Environmental Watch | In English | → Nature |
| HF | Hydrogen Fluoride | In English | → Chemistry → Chemicals |
| HF/DF | Hydrogen Fluoride/Deuterium Fluoride | In English | → Chemistry → Chemical technology |
| HFC | Heat Flow and Convection | In English | → Thermodynamics |
| HFP | Hardened Focal Plane | In English | → Optics |
| HGc-Dt-E | Mercury-Cadmium-Telluride | In English | → Chemistry → Chemical technology |
| HGE | Handbook of Geophysical Exploration | In English | → Serial publications, periodicals → Geophysics |
| HGeo | History of Geophysics | In English | → Serial publications, periodicals → Geophysics → History |
| HGF | Hepatocyte Growth Factor | In English | → Biochemistry, biophysics |
| HGP | Human Genome Project | In English | → Genetics |
| HGSC | Human Genome Sequencing Center | In English | → Genetics |
| HGT | Human Gene Therapy | In English | → Serial publications, periodicals → Genetics |
| HGVT | Horizontal Ground Vibration Test | In English | → Acoustics |
| HHV | Human Herpesvirus | In English | → Virology → Infectious diseases |
| HiA | Highlights of Astronomy | In English | → Serial publications, periodicals → Astronomy |
| HIR | Hologram Image Register | In English | → Libraries → Optics |
| HIRIS | High Resolution Imaging Spectrometer | In English | → Physics → Analytical chemistry |
| HIV | Human Immunodeficiency Virus = VIH | Virus de l'Immunodéficience Humaine | In French = VIH | Virus d'Inmunodeficencia Humana | In Asturian = VIH | Vírus da imunodeficiência humana | In Portuguese = VIDH | Virus Immunitarii Defectus Humanae | In Latin = ŽIV | Žmogaus Imunodeficito Virusas | In Lithuanian = ХИВ | Хумане имунодефицијенције | In Serbian = MIV | Menslike Immuniteitsgebreksvirus | In Afrikaans = HIV | Humani Imunodeficientni Virus | In Slovenian = ВИЧ | Вирус иммунодефицита человека | In Russian = GIB | Giza Immunoeskasiaren Birusa | In Basque |
In English | → Virology → Immunology and allergy → Infectious diseases |
| HIV | Humani Imunodeficientni Virus = VIH, VIDH, ŽIV, ХИВ, MIV, ВИЧ, GIB (look above) |
In Slovenian | → Virology → Immunology and allergy → Infectious diseases |
| HLA | Human Leucocyte Antigen | In English | → Biochemistry, biophysics |
| HMM | Hidden Markov Models | In English | → Statistics → Mathematics |
| HMPV | Humanes Metapneumovirus | In German | → Virology |
| HMR | Helgoland Marine Research | In English | → Serial publications, periodicals → 50146 → Hydrology |
| HMT | Heat and Mass Transfer | In English | → Serial publications, periodicals → Thermodynamics |
| HNMS | Hellenic National Meteorological Service | In English | → Meteorology, climatology |
| HOA | Hydroxylamine-oxydoreductase | In English | → Enzymes |
| HOBt | Hydroxybenzotriazole | In English | → Chemistry → Chemicals |
| HOE | Holographic Optical Element | In English | → Optics |
| HOLAB | Holographic Laboratory Brassboard | In English | → Optics |
| HOLIVAR | Holocene Climate Variability | In English | → Meteorology, climatology |
| HoMAI | Hologram Manufacturers Association of India | In English | → Associations → Optics |
| HOPS | Holografisch-Optische Projektionsscheiben | In German | → Optics |
| HPCRE | Handbook on the Physics and Chemistry of Rare Earths | In English | → Serial publications, periodicals → Physics → Chemistry |
| HPF | Highest Probable Frequency | In English | → Mathematics |
| HPICS | Heat Pipe Instrumentation and Control System | In English | → Thermodynamics |
| HPLC | High Performance Liquid Chromatography | In English | → Chromatography, mass spectrography |
| HPlPh | Handbook of Plasma Physics | In English | → Serial publications, periodicals → Plasma physics |
| HPLS | History and Philosophy of the Life Sciences | In English | → Philosophy, psychology → Biological sciences → Medicine → History |
| HPOL | High-Power Optics Laboratory | In English | → Research institutes → Optics |
| HPR | High Pressure Research | In English | → Serial publications, periodicals → Physics → Chemistry |
| HPSL | High Performance Smart Lid | In English | → Biological sciences |
| HQE | Haute Qualité Environnementale | In French | → Quality management → Nature and society → Environmental technology, water supply, waste management |
| HR | Homologous Recombination | In English | → Genetics |
| HR | Heat-Resistant | In English | → Thermodynamics |
| HR&T | Heat Rejection and Transport | In English | → Thermodynamics |
| HRSC | High Resolution Stereo Camera | In English | → Astronomy → Spaceflight engineering, astronautics |
| HRSO | High-Resolution Solar Observatory | In English | → Observatories |
| HRTEM | High Resolution Transmission Electron Microscopy | In English | → Physics |
| HS | Hydrogen Sulfide | In English | → Chemistry → Chemical technology |
| HS | Heat Shield | In English | → Thermodynamics |
| HS | History of Science | In English | → History |
| HSA | Heat Shield Abort | In English | → Thermodynamics |
| HSA | Health Science Authority | In English | → Medicine → Biological sciences |
| HSB | Heat Shield Boost | In English | → Thermodynamics |
| HSL | Hormonsensitive Lipase | In English | → Enzymes |
| HSPBS | Historical Studies in the Physical and Biological Sciences | In English | → Serial publications, periodicals → Physics → Biological sciences → History |
| HSS | History of Science Society | In English | → Organizations and associations → History |
| HST | Hubble Space Telescope | In English | → Astronomy → Spaceflight engineering, astronautics |
| HT | Heat Transfer | In English | → Thermodynamics |
| HT | Hadamard Transform | In English | → Mathematics |
| HT | Heat Treatment | In English | → Thermodynamics |
| HTD | Human Transcript Database | In English | → Genetics |
| HTemS | High Temperature Science | In English | → Serial publications, periodicals → Physics → Chemistry |
| HTHP | High Temperatures and High Pressures | In English | → Serial publications, periodicals → Physics → Chemistry |
| HTJR | Heat Transfer Japanese Research | In English | → Serial publications, periodicals → Thermodynamics |
| HTPB | Hydroxyl Terminator Polybutadiene | In English | → Physics → Chemical technology |
| HTPB | Hydroxyl Terminated Polybutylene | In English | → Physics → Chemical technology |
| HTrEn | Heat Transfer Engineering | In English | → Serial publications, periodicals → Thermodynamics → Engineering, technology |
| HTS | Heat Transport Section | In English | → Thermodynamics |
| HTSR | Heat Transfer Soviet Research | In English | → Serial publications, periodicals → Thermodynamics |
| HUT | Hopkins Ultraviolet Telescope | In English | → Astronomy |
| HUVEC | Human Umbilical Vascular Endothelial Cell | In English | → Biological sciences → Medicine |
| HvaOB | Hvar Observatory Bulletin | In English | → Serial publications, periodicals → Astronomy |
| HWP | Horizons in World Physics | In English | → Serial publications, periodicals → Physics |
| HydJ | Hydrogeology Journal | In English | → Serial publications, periodicals → Hydrology |
| HyInt | Hyperfine Interactions | In English | → Serial publications, periodicals → Astronomy → Physics |
| HyPr | Hydrological Processes | In English | → Serial publications, periodicals → Hydrology |
| I | Inosine | In English | → Genetics → Biochemistry, biophysics |
| I | Izoleŭcino = I | Isoleucine | In English = I | Isoleucina | In Catalan = I | Isoleucin | In Danish = I | Isoleucin | In German = I | Isoleucina | In Spanish = I | Isoleucine | In French = I | 이소류신 | In Korean = I | Izoleucin | In Croatian = I | Isoleusin | In Indonesian = I | Isoleucina | In Italian = I | איזולאוצין | In Hebrew = I | Izoleicīns | In Latvian = I | Isoleucin | In Letzeburgesh = I | Izoleucinas | In Lithuanian = I | Isoleucine | In Dutch = I | イソロイシン | In Japanese = I | Izoleucyna | In Polish = I | Isoleucina | In Portuguese = I | Изолейцин | In Russian = I | Isoleusiini | In Finnish = I | Isoleucin | In Swedish = I | İzolösin | In Turkish = I | Ізолейцин | In Ukrainian = I | 異亮氨酸 | In Chinese |
In Esperanto | → Biochemistry, biophysics |
| I | Izoleicīns = (look above) |
In Latvian | → Biochemistry, biophysics |
| I | Isoleucin = (look above) |
In Letzeburgesh | → Biochemistry, biophysics |
| I | Izoleucinas = (look above) |
In Lithuanian | → Biochemistry, biophysics |
| I | イソロイシン = (look above) |
In Japanese | → Biochemistry, biophysics |
| I | Izoleucyna = (look above) |
In Polish | → Biochemistry, biophysics |
| I | Isoleucina = (look above) |
In Portuguese | → Biochemistry, biophysics |
| I | Изолейцин = (look above) |
In Russian | → Biochemistry, biophysics |
| I | Isoleusiini = (look above) |
In Finnish | → Biochemistry, biophysics |
| I | Isoleucin = (look above) |
In Swedish | → Biochemistry, biophysics |
| I | İzolösin = (look above) |
In Turkish | → Biochemistry, biophysics |
| I | Ізолейцин = (look above) |
In Ukrainian | → Biochemistry, biophysics |
| I | 異亮氨酸 = (look above) |
In Chinese | → Biochemistry, biophysics |
| I | איזולאוצין = (look above) |
In Hebrew | → Biochemistry, biophysics |
| I | Isoleucina = (look above) |
In Italian | → Biochemistry, biophysics |
| I | Isoleusin = (look above) |
In Indonesian | → Biochemistry, biophysics |
| I | Isoleucine = (look above) |
In English | → Biochemistry, biophysics |
| I | Isoleucina = (look above) |
In Catalan | → Biochemistry, biophysics |
| I | Isoleucin = (look above) |
In Danish | → Biochemistry, biophysics |
| I | Isoleucin = (look above) |
In German | → Biochemistry, biophysics |
| I | Isoleucina = (look above) |
In Spanish | → Biochemistry, biophysics |
| I | Izoleucin = (look above) |
In Croatian | → Biochemistry, biophysics |
| I | Isoleucine = (look above) |
In Dutch | → Biochemistry, biophysics |
| I | Isoleucine = (look above) |
In French | → Biochemistry, biophysics |
| I | 이소류신 = (look above) |
In Korean | → Biochemistry, biophysics |
| IAA | International Aerospace Abstracts | In English | → Serial publications, periodicals → Astronomy → Aeronautics, aircraft → 6297 |
| IABEM | International Association for Boundary Element Methods | In English | → Associations → Mathematics |
| IACNDR | Inter-American Committee on Natural Disaster Reduction = CIRDN | Comité Interamericano para la Reducción de los Desastres Naturales | In Spanish = CIRDN | Comitê Interamericano sobre a Redução de Desastres Naturais | In Portuguese |
In English | → Organizations and associations → Natural disasters |
| IACR | International Association for Cryptologic Research (www.iacr.org) | In English | → Associations → Mathematics → Telecommunications |
| IAdEM | Internacia Asocio de Esperantistaj Matematikistoj | In Esperanto | → Associations → Mathematics |
| IadEN | ядерная энергия = IadEn | Iadernaia Energiia | In Russian |
In Russian | → Serial publications, periodicals → Nuclear, atomic, and molecular physics → Nuclear technology |
| IadEn | Iadernaia Energiia = IadEN (look above) |
In Russian | → Serial publications, periodicals → Nuclear, atomic, and molecular physics → Nuclear technology |
| IAF | Institut für Angewandte Festkörperphysik | In German | → Physics |
| IAFE | Instituto de Astronomía y Física del Espacio | In Spanish | → Astronomy |
| IAGC | Institute of Applied Genetics and Cell Biology = IAGZ | Institut für Angewandte Genetik und Zellbiologie | In German |
In English | → Research institutes → Genetics → Cytology |
| IAGZ | Institut für Angewandte Genetik und Zellbiologie = IAGC (look above) |
In German | → Research institutes → Genetics → Cytology |
| IAH | International Association of Hydrogeologists | In English | → Associations → 5325 → Hydrology |
| IAIN | International Association of the Navigation Institutes | In English | → Associations → Geodesy, cartography → Vehicle engineering |