China 
Africa 
- Handset
- Handsfree
- Handshake
- Handwriting recognition
- Hang
- Hankel matrix
- Hankel singular values
- Hankel transform
- Hans device
- Hansen solubility parameter
- Hantavirus
- Hantzsch Pyrrole Synthesis
- Haplotypes
- Happy Planet Index
- Haptens
- Haptic technology
- Hapticity
- Haptotaxis
- Harbor
- Harbours
- Hard
- Hard carbon
- Hard copy
- Hard drive
- Hard engineering
- Hard hat
- Hard infrastructure
- Hard landing
- Hard mask
- Hard problem of consciousness
- Hard spheres
- Hard tissue
- Hard water
- Hard-coded
- Hardboard
- Hardenability
- Hardened steel
- Hardening
- Hardfacing
- Hardness
- Hardscape
- Hardtop
- Hardware
- Hardware abstraction
- Hardware acceleration
- Hardware emulation
- Hardware security
- Hardware virtualization
- Hardware-based encryption
- Hardware-in-the-loop simulation
- Hardy Cross method
- Hardy field
- Hardy space
- Harmful algal bloom
- Harmonic
- Harmonic analysis
- Harmonic balance
- Harmonic conjugate
- Harmonic drive
- Harmonic functions
- Harmonic generation
- Harmonic mean
- Harmonic measure
- Harmonic numbers
- Harmonic polynomial
- Harmonic spectrum
- Harmonic tremor
- Harmonics
- Harmonized System
- Harris corner detector
- Hartley Transform
- Hartley oscillators
- Hartree-Fock
- Harvard architecture
- Harvester
- Harzburgite
- Hash chain
- Hash collisions
- Hash function
- Hash list
- Hash tables
- Hash tree
- Hashing trick
- Hashtag
- Hasse diagram
- Haswell
- Hat notation
- Hata model
- Hatchbacks
- Hatching
- Hauerite
- Haul road
- Haul trucks
- Haulage
- Hausdorff
- Hausdorff dimension
- Hausdorff distance
- Hausdorff measure
- Hausdorff space
- Hausmannite
- Haustra
- Haven
- Haversian canals
- Haversine formula
- Havex
- Havriliak-Negami relaxation
- Hawaiite
- Hawking radiation
- Hawser
- Hay fever
- Hayflick limit
- Hazard Communication Standard
- Hazard analysis
- Hazard analysis and critical control points
- Hazard and operability study
- Hazard controls
- Hazard elimination
- Hazard ratio
- Hazardous areas
- Hazardous drugs
- Hazardous materials
- Hazardous waste
- Hazards
- Haze
- Hazen-Williams
- Hazwoper
- HbA1c
- Hbcag
- HeLa
- Head
- Head cuts
- Head direction cells
- Head gasket
- Head injury
- Head of radius
- Head unit
- Head-mounted display
- Head-on collision
- Headaches
- Header file
- Headers
- Headframe
- Heading
- Heading indicator
- Headphones
- Headquarters
- Headroom
- Headset
- Headwall
- Headward erosion